vmware custom interview questions

How VMWare Kernel different from other kernels? VMWare kernel is a proprietary kernel that means that it is a registered kernel by VMWare Company and it is not based on any other kernel architecture or any other operating system. VMWare consists of a kernel that requires an operating system to boot it. A service console is being provided when VMWare kernel is booted.

What are the features provided by VMWare for easy access? VMWare provides several features to make it easy for the user to access and maintain it. The features are as follows: • VMWare provides web browser interface • It provides easy to use wizard to configure the settings • It provides tools to easily create hosts and maintain it from one place • It provides easy maintenance of Virtual machines • It provides easy graphics to configure the VMWare settings for security

What are the features of VMWare Player? VMWare player is a stand-alone player that comes with the installation of VMWare also. The features that make it more popular are as follows: • Creation of virtual machines can be done with easy install options. The creation and installation can be done directly to the system. • VMWare Player can run any virtual machine and it can be used by anyone, anywhere. It allows quick and easy access, to take the advantage of security, portability and flexibility to manage the virtual machines. • VMWare player allows sharing of virtual machines with other computers or users.

What are the different components used in VMWare infrastructure? The different and major components used in VMWare infrastructure is as follows: 1. VMWare infrastructure consists of the lowest layer which acts as a ESX server host. 2. VMWare infrastructure also use the virtual centre server that keep tracks of all the VM related images and manage it from one point. 3. VMWare infrastructure (VI) client: this allows the client to interact with user's applications that are running on VMWare. 4. Web browser is used to access the virtual machines. 5. License server is used to create a server that provides licensing to the applications 6. Database servers are used to maintain a database.

5. What are the benefits of virtualization? Virtualization is a creation of virtual machines and to manage them from one place. It allows the resources to be shared with large number of network resources. Virtualization is having lots of benefits and they are as follows: 1. It helps in saving lots of cost and allows to easily maintaining it, in less cost. 2. It allows multiple operating systems on one virtualization platform. 3. It removes the dependency of heavy hardware to run the application. 4. It provides consolidating servers that are used for crashing of a server purpose 5. It reduces the amount of space being taken by data centres and company data.

6. What is the purpose of a Hypervisor?

Hypervisor is a program that manages the virtual machine. It also act like virtual machine manager that manages the many virtual machines from one place. It allows multiple operating system to share single hardware host. Each operating system in this consists of its own defined space consisting of space, memory and processor. It is used as a controller program to control host processors and resources. It separates out the layer between many operating systems so that one can't conflict with another one.

7. How ESX server related to VMWare? ESX server is the enterprise edition of VMWare. It provides server virtualization platform that allows many operating systems to be shared together in a convenient way and consists of a centralized management platform that is also known as virtual centre. ESX server is a virtualization technique that is used to create cloud applications and allows easy development of cloud platforms. It is related to VMWare as it is the upper layer of it.

8. What is the difference between ESX and GSX server? GSX server acts as type 2 hypervisor that gets installed on the host operating system’s hardware like windows and Linux. VMWare workstation gets mixed up with GSX server to provide it more functionality to run your applications and operating systems. ESX server on the other hand, is type 1 hypervisor that runs its software directly on the system’s hardware and it doesn’t require any operating system prior to its installation. It is level 0 hypervisor and it has its own operating system.

9. What is the use of VMWare workstation? VMWare workstation is software that allows user to run more than one operating system in there system. It provides virtualization to run different applications on many operating systems at a single time. It saves the current configuration of operating system for the user in the form of virtual machines. VMWare allows user to view there application and work with so many different OS without even switching between the OSs.

10. What are the different types of extensions used by VMWare? 1. .log: is used to keep a log file to maintain a key for VMWare. This file allows user to see the problems encountered during any installation or while using VMWare. 2. .nvram: is used to store the state of the virtual machine in system’s BIOS. 3. .vmdk: is a virtual disk file that is used to store the content of virtual machine. 4. .vmsd: stores the information and metadata of the system’s snapshots. 5. .vmsn: is used to store the snapshot state. It stores both the running state and the time when you have taken it. 6. .vmss: stores the suspended state of a virtual machine. 7. .vmtm: stores the configuration team data. 8. .vmx: store the primary configurations for the new virtual machine.

11. How virtual machine’s concept is different for host and guest systems? Host system is the system that runs the operating system and over which the virtual platform can be installed. The virtual platform that runs another operating system is called as guest operating system. Host and guest can be connected with each other by using the virtual machines. A host system that runs all together its own operating system is called as virtualization host and the guest operating system will be that, which get installed over that operating system.

12. What are some major differences between VMWare Server and ESX server? • ESX server is a bare metter virtualation platform that is a physical server whereas, VMWare server needs an operating system to run itself. • ESX server is type 1 hypervisor virtualization platform whereas, VMWare server is a type-2 hypervisor virtualization

platform. • ESX server gives better performance then VMWare server, due to less overhead. • ESX server have more features available then VMWare server. • VMWare server is good to be used on small platforms and with less resources but, ESX server requires high specifications.

13. What is the use of Para-virtualization? Para-virtualization is a virtualization technique that allows similar virtual machines to be created on particular hardware. It allows many operating systems to run on host hardware at the same time. It makes good use of resources like processors, memory and networking. It acts as a virtual machine monitor that has high performance and more efficient. It is used for development, testing and production of the virtual machines. It also good in disaster recovery by moving the guest virtual machine till the hardware is being repaired.

14. Why snapshots are really important in VMWare? Snapshots are images that is been taken at a particular point from the virtual guest operating system. The snapshot consists of the virtual machine configurations, memory and the devices that were present at the time of the snapshot. By doing this, you can return back to virtual machine which might have become corrupted or might not be working. Snapshots can be taken anytime according to your need and requirement. Snapshots can be saved and then system can be reverted back in case of any disaster happened to your operating system.

15. What are the disadvantages associated with VMWare virtualization platform? The disadvantage of VMWare virtualization platform is as follows: • VMWare concept requires the knowledge of the concept. • It requires money to buy the resources required for virtualization platform. • It requires high end server with lots of high end configuration and specification that increases the cost. • It requires different technologies that have to be implemented for the enterprise virtualization systems. • Reliability decreases and cost increases in case of the system failures.

101 VMware & Windows Interview Questions : Part 1

1. Windows 2003 vs Windows 2008

o o o o o o o o o o o o o

2.

RODC WDS instead of RIS Services have been changed as roles - server manager Introduction of hyper V- only on 64 bit versions Enhanced event viewer Bitlocker feature Server core installation without GUI MMC 3.0, with three pane view Key management services(KMS) to activate Windows OS without connecting to Microsoft site Performance enhancement using technologies like Windows SuperFetch,ReadyBoost and Readydrive Windows Aero user interface Instant search Support for IPv6 in DNS

ESX vs ESXi

o o o o

ESXi has no service console which is a modified version of RHEL ESXi is extremely thin hence results in fast installation + fast boot ESXi can be purchased as an embedded hypervisor on hardware ESXi has builtin server health status check

3.

ESXi 4.1 vs ESXi 5.0 - Migration

o o

4.

ESXi 4.1 vs ESXi 5.0 - Features

o o o o o o o o o o o o o o

5.

Local upgrade from CD VMware update manager (only supports upgrade of ESX/ESXi 4.x to ESXi 5.0)

vSphere Auto deploy Storage DRS HA - Primary/secondary concept changed to master/slave Profile driven storage VMFS version - 3 → 5 ESXi firewall VMware hardware version - 7 → 8 VMware tools version - 4.1 → 5 vCPU - 8 → 32 vRAM - 256 → 1 TB VMs per host - 320 → 512 RAM per host - 1TB → 2TB USB 3.0 support vApp

FSMO roles

o o o

Schema Master Domain naming master Infrastructure master

o o

6.

PDC Emulator RID master

GPO

o o o o o

GPO Templates (ADMX) Block inheritance Enforced Loopback policy

7.

Forest and Domain concepts

8.

OSI layer o o o o o o o

9.

Application Layer Presentation Layer Sessions Layer Transport Layer Network Layer DataLink layer Physical Layer

ASA - site to site VPN

10.

HA 5.0 o o o o

o

o o

o

o

Uses an agent called FDM - Fault domain manager HA now talks directly to hostd instead of using vcenter agent vpxa Master/slave concept Master  monitors availability of hosts/VMs  manages VM restarts after host failure  maintains list of all VMs in each host  restarting failed VMs  exchanging state with vcenter  monitor state of slaves Slave  monitor running VMs and send status to master and performs restart on request from master  monitors master node health  if master fails, participates in election Two different heartbeat mechanisms - Network heartbeat and datastore heartbeat Network heartbeat  Sends between slave and master per second  When slave is not receiving heartbeat from master, checks whether it is isolated or master is isolated or has failed Datastore heartbeat  To distinct between isolation and failure  Uses „Power On‟ file in datastore to determine isolation  This mechanism is used only when master loses network connectivity with hosts  2 datastores are chosen for this purpose

Isolation response  PowerOff  Leave Powered On  Shutdown

11. vMotion o vMotion enables live migration of running virtual machines from one host to another with zero downtime o Prerequisites i. Host must be licensed for vMotion ii. Configure host with at least one vMotion n/w interface (vmkernel port group) iii. Shared storage (this has been compromised in 5.1)

iv. v. vi. vii. viii. ix. x.

12.

Same VLAN and VLAN label GigaBit ethernet network required between hosts Processor compatibility between hosts vMotion does not support migration of applications clustered using Microsoft clustering service No CD ROM attached No affinity is enabled vmware tools should be installed

RAID o o o

Redundant Array of Independent disks A category of disk drives that uses 2 or more drives in a combination for redundancy and performance Most common RAIDs: RAID 0(Striped), RAID 1(Mirroring), RAID 5

13.

Backup types o Backup types i. Full backup - Will take the backup of all selected files and reset the archive bit ii. Copy backup - Will take the backup of all selected files but does not reset the archive bit iii. Incremental backup - Will take the backup of files whose archive bits are set and resets it after backup iv. Differential backup - Will take the backup of files whose archive bits are set but does not reset it after backup

14.

2003 → 2008 migration o o o o o o

Can be done only by logging in to Windows 2003 server Min of Windows 2003 SP1 required Can be migrated only to same version, except for Windows server 2003 standard which can be migrated to either standard or enterprise Extra space of 30 GB required prior migration Cannot upgrade to server core Perform forestprep and domainprep to 2008 using 2008 cd before migrating. (Copy sources/adprep folder for this)

15.

ESXi update manager

16.

Global Catalog o o o o o o o

o

o

Global catalog (GC) is a role handled by domain controllers in an Active directory model. The global catalog stores a full copy of all objects in the directory for its host domain and a partial copy of all objects for all other domains in the forest. „Partial copy‟ refers to the set of attributes that are most used for searching every object in every domain. All domain controllers can be promoted as a GC. GC helps in faster search of AD objects. The replicas that are replicated to the global catalog also include the access permissions for each object and attribute. If you are searching for an object that you do not have permission to access, you do not see the object in the list of search results. Users can find only objects to which they are allowed access. Global catalog server clients depend on DNS to provide the IP address of global catalog servers. DNS is required to advertise global catalog servers for domain controller location. By default, first DC of in a forest will be a global catalog server

17.

Basic networking concepts

18.

RODC o o o o o o

New feature in Windows 2008 Only have the read only copy of directory database RODC will have all the objects of a normal DC in read only mode. But this doesn‟t include passwords. RODC does not store password of accounts. Updates are replicated to RODC by writable DC Password caching : A feature which enables RODC to cache password of the logged in users. Password Replication Policy: Determines whether the password can be cached or not.

o

DNS can be integrated with RODC but will not directly register client updates. For any DNS change, the RODC refers the client to DNS server that hosts a primary or AD integrated zone

19.

NAS vs SAN o Both used as storage solution o NAS can be used by any device connected using LAN whereas SAN is used only by server class devices with SCSI o NAS is file based whereas SAN is block based storage o NAS is cheap while SAN is expensive o SAN is comparatively faster than NAS

20.

What is DRS? Types of DRS o Distributed Resource Scheduler o It is a feature of a cluster o DRS continuously monitors utilization across the hosts and moves virtual machines to balance the computing capacity o DRS uses vMotion for its functioning o Types of DRS i. Fully automated - The VMs are moved across the hosts automatically. No admin intervention required. ii. Partially automated - The VMs are moved across the hosts automatically during the time of VM bootup. But once up, vCenter will provide DRS recommendations to admin and has to perform it manually. iii. Manual - Admin has to act according to the DRS recommendations

21.

DRS prerequisites o Shared storage o Processor compatibility of hosts in the DRS cluster o vMotion prerequisites

22.

vMotion is not working. What are the possible reasons? o Ensure vMotion is enabled on all ESX/ESXi hosts o Ensure that all vmware pre requisites are met

o o o

23.

Verify if the ESXi/ESX host can be reconnected or if reconnecting the ESX/ESXi host resolves the issue Verify that time is synchronized across environment Verify that the required disk space is available

What happens if a host is taken to maintenance mode o Hosts are taken to maintenance mode during the course of maintenance o In a single ESX/ESXi setup, all the VMs need to be shutdown before getting into maintenance mode o In a vCenter setup If DRS is enabled, the VMs will be migrated to other hosts automatically. o

24. How will you clone a VM in an ESXi without vCenter o Using vmkftools o Copy the vmdk file and attach to a new VM o Using VMware converter

25.

Explain traverse folder o Allows or denies moving through a restricted folder to reach files and folders beneath the restricted folder in the folder hierarchy. o Traverse folder takes effect only when the group or user is not granted the "Bypass traverse checking user" right in the Group Policy snap-in. This permission does not automatically allow running program files. 1. Maximum number of LUNs that can be attached to a host (ESXi 5.0) o 256

2.

Maximum number of vCPUs that can be assigned to a VM (ESXi 5.0) o 32

3.

What are the uses of ntdsutil tool? o Some of the main uses of ntdsutil tool i. Authoritative Restore - Authoritatively restores the Active Directory database or AD LDS instance ii. ifm - Create installation media for writable and RODC setups (Offline DC provisioning) iii. metadata cleanup - Cleans up objects of decommissioned servers iv. roles - Transfers and seizes operations master roles v. set DSRM password - Resets DSRM administrator password vi. snapshot - Manages snapshots of the volumes that contain the Active Directory database and log files

4.

FSMO roles and its failure scenarios o http://www.systemadminguide.in/2013/07/fsmo-roles-in-nutshell.html

5.

IPv6 addresses and its DNS record o 128 bit address o Represented as 8 groups of 4 hexadecimel digits seperated by colons o Represented by „AAAA‟ record in DNS o Uses DHCP v6 for addressing

6.

Loadbalancer vs Clustering o Clustering i. Cluster is a group of resources that are trying to achieve a common objective, and are aware of one another. ii. Clustering usually involves setting up the resources (servers usually) to exchange details on a particular channel (port) and keep exchanging their states, so a resource‟s state is replicated at other places as well. iii. It usually also includes load balancing, wherein, the request is routed to one of the resources in the cluster as per the load balancing policy o Load Balancing

.

7.

Used to forward requests to either one server or other, but one server does not use the other server‟s resources. Also, one resource does not share its state with other resources.

Software installation using group policy o This can be done using 2 methods i. Assigning ii. Publishing o Assign : . If you assign the program to a user, it is installed when the user logs on to the computer. When the user first runs the program, the installation is completed. i. If you assign the program to a computer, it is installed when the computer starts, and it is available to all users who log on to the computer. When a user first runs the program, the installation is completed. o Publish : . You can publish a program distribution to users. i. When the user logs on to the computer, the published program is displayed in the Add or Remove Programs dialog box, and it can be installed from there. o msi packages are used for installation. Normal exe would not work. o Windows cannot install the software while the user is already logged on. The user need to log off and log in

8. Group policy security filtering for users. Which all users are in there by default. Members of Authenticated Users group o Security filtering is a way of refining which users and computers will receive and apply the settings in a Group Policy object (GPO) o In order for the GPO to apply to a given user or computer, that user or computer must have both Read and Apply Group Policy (AGP) permissions on the GPO, either explicitly, or effectively through group membership o By default, all GPOs have Read and AGP both Allowed for the Authenticated Users group. o The Authenticated Users group includes both users and computers. This is how all authenticated users receive the settings of a new GPO when it is applied to an organizational unit, domain or site

9.

Relevance of host file and its location o Came before the concept of DNS o An FQDN is first checked in Host file o Location : C:\Windows\System32\Drivers\etc

10.

L3 switch vs Routers o L3 switches just have the ethernet ports only whereas the routers have WAN interfaces o QoS is not available with L3 switches whereas in routers it can be enabled o Routers have expansion slots and cards that allow them to use different media types, like serial connections for T1 and T3 circuits o Routers are more intelligent in handling packets o L3 switches does not support NAT

11.

VLAN vs Subnet o VLAN works at layer 2 while subnet is at layer 3 o Subnets are more concerned about IP addresses. o VLANs bring more network efficiency o Subnets have weaker security than VLANs as all the subnet uses the same physical network

12.

Contents of System state backup o Registry o COM+ Class Registration database o Boot files, including the system files o System files that are under Windows File Protection o Active Directory directory service (If it is domain controller) o SYSVOL directory (If it is domain controller) o Cluster service information (If it is a part of a cluster) o IIS Metadirectory (If it is an IIS server) o Certificate Services database (If it is a certificate server)

13.

Incremental vs Differential backups o Incremental backup - Will take the backup of files whose archive bits are set and resets it after backup o Differential backup - Will take the backup of files whose archive bits are set but does not reset it after backup

14.

Robocopy o Microsoft tool used for copying files effectively o It has plenty of options to manage the copy process

15.

How do you patch microsoft applications? Frequency of patches released by Microsoft o The Microsoft applications can be patched using WSUS o In WSUS, we can create several computer groups to manage this patch process. o MS patches are released once in a month

16.

Explain GPO, GPC & GPT o GPO - Group Policy Object : Refers to the policy that is configured at the Active Directory level and is inherited by the domain member computers. You can configure a GPO at the site level, domain level or OU level. GPO stores policy settings in two locations GPC and GPT o GPO behaviour : Local Policy > Site GPO > Domain GPO > OU GPO > Child OU GPO o GPC - Group Policy Container :This is the AD portion of the group policy. This can be viewed using ADSI edit. It stores version information, status information, and other policy information. When you create a new GPO, an AD object of class groupPolicyContainer gets created under the System\Policies container within your AD domain o GPT - Group Policy Template : The GPT is where the GPO stores the actual settings. It stores software policy script, and deployment information.

o

17.

GPT is stored in SYSVOL share (\\DomainNameHere\SYSVOL\Policies) whereas GPC is stored in the AD

What is CPU affinity in VMware? Its impact on DRS? o CPU refers to a logical processor on a hyperthreaded system and refers to a core on a non-hyperthreaded system o By setting CPU affinity for each VM, you can restrict the assignment of VMs to a subset of available processors o The main use of setting CPU affinity is when there are display intensive workloads which requires additional threads with vCPUs. o DRS will not work with CPU affinity

http://frankdenneman.nl/2011/01/11/beating-a-dead-horse-using-cpu-affinity/

18.

.

VMversion 4 vs VMversion 7 o Version 4 i. Runs on ESX 3.x ii. Max supported RAM 64 GB iii. Max vCPUs 4 iv. MS cluster is not supported v. 4 NICs/VM vi. No USB Support o Version 7 Runs on vSphere 4.x i. Max supported RAM 256 GB ii. Max vCPUs 8 iii. MS cluster is supported iv. 10 NICs/VM v. USB support

19.

What happens to the VMs if a standalone host is taken to maintenance mode? o In case of standalone servers , VMware recommends that VMs should be powered off before putting the server in maintenance mode

o o

If we put the standalone host in maintenance mode without powering off the VMs, it will remain in the „entering maintenance mode‟ state until the VMs are all shutdown When all the VMs are powered down, the host status changes to „under maintenance‟

http://pubs.vmware.com/vsphere-4-esxvcenter/index.jsp#using_drs_clusters_to_manage_resources/c_using_maintenance_mode.html

20.

What is new in Windows server 2012 o Server core improvements: no need of fresh installation, you can add/remove GUI from server manager o Remotely manage servers , add/remove roles etc using Server manager-manage 2008 and 2008 R2 with WMF 3.0 installation, installed by default in Server 2012 o Remote server administration tools available for windows 8 to manage Windows server 2012 infrastructure o Powershell v3 o Hyper-V 3.0 i. supports upto 64 processors and 1 TB RAM per virtual machine ii. upto 320 logical hardware processors and 4 TB RAM per host iii. Shared nothing live migration, move around VMs without shared storage o

o

ReFS(Resilient file system), upgraded version of NTFS- supports larger file and directory sizes. Removes the 255 character limitation on long file names and paths, the limit on the path/filename size is now 32K characters! Improved CHKDSK utility that will fix disk corruptions in the background without disruption

21.

How does the backup software recognize that a file has changed since last backup? o The files use a bit called archive bit for tracking any change in the file. o The backup softwares normally checks the archive bit of the file to determine whether the file has to be backed up or not

22.

How can you edit a vm template? o The VM templates cannot be modified as such o First , the VM template have to be converted to a virtual machine o After making necessary machines in the virtual machine, convert the virtual machine back to template

23.

VMware configuration maximums ESXi 5.5

ESXi 5.1

ESXi 5.0

ESXi 4.x

32 1 TB 10 1 TB

8 255 GB 10 2 TB for 8MB block

160 2 TB 256 64 TB 512

160 1 TB 256 64 TB 320

VMs vCPU RAM vNIC VMDK size

64 1 TB 10 62 TB

64 1 TB 10 1 TB Hosts

Logical CPU Memory LUNs LUN size Virtual Machines

320 4 TB 256 64 TB 512

160 2 TB 256 64 TB 512

24. What is the major difference between Windows server 2008 and windows server 2012 in terms of AD promotion?

In Win 2012, dcpromo has been depreciated. In order to make a Windows server 2012 to a domain controller, the ADDS service has to be installed from the server manager. After installation, run the post-deployment configuration wizard from server manager to promote the server as AD

25.

VMware hardware version comparison

 What is vSAN? 

It is a hypervisor-converged storage solution built by aggregating the local storage attached to the ESXi hosts managed by a vCenter.

 Recommended iSCSI configuration? 

A separate vSwitch, and a separate network other than VMtraffic network for iSCSI traffic. Dedicated physical NICs should be connected to vSwitch configured for iSCSI traffic.

 What is iSCSI port binding ? 

Port binding is used in iSCSI when multiple VMkernel ports for iSCSI reside in the same broadcast domain and IP subnet, to allow multiple paths to an iSCSI array that broadcasts a single IP address.

 iSCSI port binding considerations ? 

Array Target iSCSI ports must reside in the same broadcast domain and IP subnet as the VMkernel port.



All VMkernel ports used for iSCSI connectivity must reside in the same broadcast domain and IP subnet.



All VMkernel ports used for iSCSI connectivity must reside in the same vSwitch.



Currently, port binding does not support network routing.

 Recommended iSCSI configuration of a 6 NIC infrastructure ? (Answer changes as per the infrastructure requirements) 

2 NICs for VM traffic



2 NICs for iSCSI traffic



1 NIC for vMotion



1 NIC for management network

 Post conversion steps in P2V 

Adjust the virtual hardware settings as required



Remove non present device drivers



Remove all unnecessary devices such as serial ports, USB controllers, floppy drives etc..



Install VMware tools

 Which esxtop metric will you use to confirm latency issue of storage ?



esxtop --> d --> DAVG

 What are standby NICs 

These adapters will only become Active if the defined Active adapters have failed.

 Path selection policies in ESXi 1. Most Recently Used (MRU) 2. Fixed 3. Round Robin

 Which networking features are recommended while using iSCSI traffic 

iSCSI port binding



Jumbo Frames

 Ports used by vCenter 

80,443,902

 What is 'No Access' role 

Users assigned with the 'No Access' role for an object, cannot view or change the object in any way

 When is a swap file created 

When the guest OS is first installed in the VM

 The active directory group, where the members will be ESXi administrators by default. 

ESX Admins

 Which is the command used in ESXi to manage and retrieve information from virtual machines ? 

vmware-cmd

 Which is the command used in ESXi to view live performance data? 

esxtop

 Command line tool used in ESXi to manage virtual disk files?



vmkfstools

 Port used for vMotion 

8000

 Log file location of VMware host 

\var\log\vmware

 Can you map a single physical NIC to multiple virtual switches ? 

No

 Can you map a single virtual switch to multiple physical NICs? 

Yes. This method is called NIC teaming.

 VMKernel portgroup can be used for: 

vMotion



Fault Tolerance Logging



Management traffic

 Major difference between ESXi 5.1 and ESXi 5.5 free versions 

Till ESXi 5.1 free version there was a limit to the maximum physical memory to 32 GB. But from 5.5 onwards this limit has been lifted.

 What is IPAM server in Windows server 2012? 

IPAM is IP Address Management server in Windows Server 2012. It enables central management of both DHCP and DNS servers. It can also be used to discover, monitor, and audit DHCP and DNS servers.

 How to promote a server to domain controller in Windows server 2012? 

DCPROMO was the conventional tool used to promote a normal server to DC. This is now deprecated in Server 2012.



In Server 2012, you can convert a server into DC using the server manager console. Under Server Manager, add a new role "Active Directory Domain Services"

REAL TIME SCENARIO Issue While performing vMotion, the operation fails at 14% with the below error : A general system error occurred: Migrtion to host failed with erro Connection closed by remote host, possibly due to timeout (0xbad003f). Migrate virtual machine:A general system error occurred: Migration to host failed with error Connection closed by remote host, possibly due to timeout (0xbad003f). vMotion migration [-1062729272:1406020861428172] (19-71629048648008) failed to receive... Scenarios Scenario 1: Your management network and vmotion network are in the same subnet using the same physical NIC.

Consider the case, where the management network and vmotion network are in the same subnet and you have assigned a VLAN id to the vMotion network, the operation fails at 14%. My first point will be to avoid using same IP subnet for both management and vmotion networks. Because if you use the same subnet, all the vmotion traffic will be forwarded to the physical NIC connected to the management network. This is because, by default all traffic from vmkernel portgroups from the same subnet will be forwarded to the first NIC configured in the ESXi for that IP subnet. Obviously this will be the management network. And if you still stick to the plan of using same subnet, please make sure that you have not assigned any VLAN id to the vMotion portgroup.

What happens when we assign a VLAN to the vMotion portgroup ? vMotion vmknic will try to communicate with the default gateway and since the default gateway is not tagged with the VLAN id you choose for vMotion, the operation fails. Scenario 2: Your management network and vmotion network are in the same subnet using different physical NIC (may be using different vswitches as well). The comments in the above scenario applies to this scenario also. It doesn't matter if you have created a new vSwitch or a new portgroup or a dedicated physical NIC for the vmotion network, if your management network is in the same subnet, do not assign a VLAN id to the portgroup. Scenario 3: Your management network and vmotion network in different subnet. In this case you need to check the physical switch configuration.

Scenario You have a single vmdk file of 200 GB and it has two logical volumes C & D with 100 GB each. Suppose you need to add another 100 GB to the D drive making it 200 GB. What would you do ? The steps are simple and straight forward.



Change the VMDK size using vSphere client to 300 GB (Exisiting 200 GB + required space).



Log in to the VM and ensure that the added disk space is available to the VM as 'Unallocated' space



Execute the below commands in command prompt o

diskpart

o

list volume

o

select volume

o

extend

Symptom: Eth0 interface will not be present for a Centos VM after cloning. Only the loopback networking interface will be available. If you try to turn up the interface manually (using the command ifup eth0 or ifup-eth0), you will receive the below error. Device eth0 does not seem to be present, delaying initialisation Root Cause: When you clone a Centos VM from a template, a new NIC card will be created for the cloned VM. In other

terms, a new MAC address will be generated for the NIC of the cloned machine. This change happens only in VMware perspective and no modification is made in Centos. Therefore the kernel will be still searching for the NIC with old MAC address and hence fails.

Resolution: 1. Update the exisiting ethernet configuration file to reflect the new MAC address. Check the new MAC address using vSphere client and modify the ifcfg-eth0 interface configuration using the command:

vi /etc/sysconfig/networking/devices/ifcfg-eth0 Replace HWADDR with the new MAC address 2. Remove the kernel's networking interface rules file rm -f /etc/udev/rules.d/70-persistent-net.rules 3. Reboot the VM

T

he memory usage of SQL servers is always a hot topic among the system administrators. Any system administrator who handles a SQL server in their environment would have definitely faced this issue. Before going on to the memory monitoring of SQL, we should have answers to the below questions :

1. What does SQL do with the memory ? 2. Does it handle memory in the same way as other applications do ? SQL server uses memory for :



Caching raw data



Working on your queries



Caching execution plans

The memory management of SQL is different when compared to other applications. SQL is an application with intense I/O operations. Since I/O operations on disk is time consuming, the SQL server uses 'Buffer Management' mechanism. Buffer management has two mechanisms :



'Buffer manager' to access and update database pages



'Buffer cache/pool' to reduce database file I/O

Buffer manager is responsible for handling all read/write operations in the buffer, whereas the normal select, update etc..operations are handled by the database manager. So when does a system administrator confirms that a memory upgrade is required? There are performance counters which helps system administrator on this. Will discuss about the main performance counters for analyzing this. (Performance monitors can be accessed by running 'perfmon' in run) SQLServer:Buffer Manager Buffer cache hit ratio Represents the percentage of pages found in the buffer cache without having to read from disk. A higher value for BCHR normally represents a better memory management. When this value dips, we should upgrade the RAM. The value is expected to be 100%. Page life expectancy This metric represents the number of seconds a page will stay in the buffer pool without references. In other words, this amount represents cached raw data. Higher the value, better it is. The metric is measured in secs. As a thumb rule, the value should be above 300s. SQLServer:SQL Statistics Batch requests/sec This metric represents the number of batch requests the server is receiving per second. In other words, how busy is my sql server due to incoming requests. Compilations/sec This value represents the number of times SQL Server compiles an execution plan per second. We cannot judge the performance with this metrix alone. The performance is deteremined when this metric is compared with Batch requests/sec. As a thumb rule, if the value is less than 10% of the Batch requests/sec, then the performance is desirable. Whereas if the sql server is forced to compile more than 10% of Batches requests/sec then we should understand that there is not enough memory to store the execution plans and we should consider a memory upgrade. For example: If your Batch requests/sec is 2000 and if your compilations/sec is less than 200 , then the value is desirable. SQLServer:Memory Manager Memory grants pending Represents the number of queries that are waiting for memory before they can even start. Any value greater

than 0 represents a memory issue. Target Server Memory This metric represents the ideal amount of memory the server can consume. This value is almost equal to the RAM (if no limit is set using the SQL management studio). Total server memory This metric represents the amount of memory the server has committed using the memory manager. This counter shows what is actually used and the value will be low upon starting, and will increase gradually as the SQL server brings pages to its buffer pool and finally reaches a steady state. When this reaches steady state, this will be almost equivalent to the Target Server Memory. Once it reaches the steady state, the value is not expected to dip. If this dips, it represents the memory deallocation due to memory requirement from OS or other applications. If this value is higher than target, then your server could benefit from additional RAM. All these counters are just direction pointers. Please don't rely on one counter alone to confirm the requirement of memory upgrade.

Issue You will find software iscsi adapter missing in ESXi Resolution

1. Log in to the vSphere Client 2. Select the configuration tab 3. Select Storage Adapters 4. Click on the Add option 5. You will be given the option to add Software iSCSI adapter Steps for cloning VM using SSH:



SSH to the ESXi host



Identify the path of the source (say, /vmfs/volumes/datastore1/SourceVM/where sourceVM is the name of the source VM)



Create a new folder in the desired datastore

mkdir /vmfs/volumes/datastore1/DesintationVM where DestinationVM is the name of the new VM



Clone the sourceVM vmdk to the newly created folder DestinationVM

vmkfstools -i /vmfs/volumes/datastore1/SourceVM/sourceVM.vmdk /vmfs/volumes/datastore1/DesintationVM/DesintationVM.vmdk



Once cloning is completed, proceed with the creation of the new VM using vSphere client



In the option where you need to provision the harddisk for the new VM, choose 'Use an existing virtual disk'



Browse and point the newly cloned vmdk file

below error: “Failed to start the virtual machine. Module DevicePowerOn power on failed. Unable to create virtual SCSI device for scsi…”

Cause You might have tried to PowerOn a VM with ESXi incompatible vmdk file. This VMDK file will be compatible only with VMware workstation, VMware servers etc and not with the ESXi. Resolution Make the vmdk file compatible with ESXi.

Steps:

- Remove the vmdk file from the VM. (Only from the VM!!!) - Connect to the ESXi box using putty - Execute the below command to convert the existing vmdk file to new ESXi compatible vmdk vmkfstools -i existing_vmdk_location new_vmdk_location

- Point the VM with the newly formatted vmdk file and Power On. That‟s it….

Symptoms VMs will be shown as inaccessible in the vCenter

Reason A VM can become inaccessible due to any of the below reason:



Issue with the ESXi servers



Issue with the vCenter



Issue with the datastore

Resolution In all the three cases these are the below three troubleshooting steps:

First step will be to restart the management agents in the ESXi.



Login to the ESXi using SSH



Run any of the below commands to restart the management agents

/etc/init.d/hostd restart /etc/init.d/vpxa restart or services.sh restart If this step did not resolve the issue for you, try the second step Second step will be to remove the VM from the inventory and add using the vmx file



Right click on the affected VM



Choose the option 'Remove from the Inventory' (Be cautious about this action...Do not delete the VM)



After this step, go to the vmx location of the VM



Right click on the VM and 'Add to the Inventory'

This step will definitely resolve your issue. But this step works fine only when we know the vmx location of the VM. If you are not sure about the vmx location you will end up in adding incorrect VMs. Keep in your mind that you cannot access the vmdk location to find the vmx path when the VM is inaccessible.

In these kind of situations, the best method is to use command line, the third step!!!



Login to the ESXi hosting the inaccessible VM using SSH



Run the below command to know the vmid of the VMs in the host

vim-cmd vmsvc/getallvms

You will receive a message "Skipping invalid VM '144' " along with the details of valid VMs. The skipped VM will be the invalid one. The value '144' represents the vmid of the VM.



Now run the below command to reload the invalid VM

vim-cmd vmsvc/reload vmid where vmid is the id of the invalid VM

That will save your day!!!

Scenario When we try to reduce or shrink the size of an existing vmdk file, the operation fails. Resolution There is no option to reduce the size using vSphere client. For this you may need to use putty or cli. Please remember to delete unwanted data from the OS and to shrink the partition internally using the diskmgmt.msc tool. After shrinking , perform the below: 

Login to the ESXi using putty



Browse to the vmdk location (eg: cd vmfs/volumes/datastore1/VMname)



Take a backup of the existing vmname.vmdk and vmname-flat.vmdk files using thecp command in linux (cp filename backup_filename)



Open the vmdk file using vi editor o



vi vmname.vmdk

Modify the value corresponding to RW to the required disk space. If you need to shrink the file to xGB, use the value : x*1024*1024*2. For eg: if you want to shrink the disk to 25GB, give the value 25*1024*1024*2= 52428800



Once finished save the file and use vmkfstools command to clone a disk using the new settings.

o



Remove the old vmdk files o



rm vmname.vmdk rm vmname-flat.vmdk

Once removed, again use the vmkfstools to clone vmdk files of the same old name. o



vmkfstools -i vmname.vmdk vmname-new.vmdk

vmkfstools -i vmname-new.vmdk vmname.vmdk

Using vi client , remove the hard disk from virtual machine and add again.

Scenario When we use thin provisioned vmdk, the size of the vmdk expands as we pile up data in the OS. But if we delete some data from OS, the reclaimed space in the OS will not be reclaimed from the vmdk. It will continue to occupy the maximum space it have ever used after creation. Resolution

There is no resolution to reduce the size using vSphere client. For this you may need to seek the help of putty or cli.

- Login to the ESXi using putty - Browse to the vmdk location (eg: cd vmfs/volumes/datastore1/VMname - List the available vmdk files in this location using the command:

ls –lh *.vmdk

- To know the actual size occupied by the vmdk file < du –h *.vmdk

- To shrink the size of the vmdk file vmkfstools -K AD01.vmdk

- Re check the actual size of vmdk now. You will feel the difference !!!

Resizing an IDE virtual disk 1. Remove the IDE vmdk from the VM 2. Edit the “vmdk” file (can be found under cd /vmfs/volumes///) 3. Change ddb.adapterType from “ide” to “lsilogic” 4. Add the IDE vmdk to the VM 5. Change the size of the disk 6. Remove the IDE vmdk from the VM 7. Edit the “vmdk” file 8. Change ddb.adapterType from “lsilogic” to “ide” 9. Add the IDE vmdk to the VM 10. Power on the VM and “extend” the partition within Windows 7

How to remove Dead or Error iscsi targets from ESXi | VMware Issue:Sometime we may find an iscsi target associated to an iscsi adapter being greyed out and marked as Dead or Error. In VMkernel log you may receive an error as given below: WARNING: NMP: nmpDeviceAttemptFailover:658:Retry world failover device "naa.6090a05850f3465b871325e61b6af905" - failed to issue command due to Not found (APD), try again... This is a result of an improper deletion of a LUN/iscsi target from the storage adapter. Resolution:Enter the host into maintenance mode (Just to be safe) esxcfg-rescan -d vmhba3 Replace vmhba id with the id of your vmhba adpater. Ensure that you are not receiving any errors by checking vmkernel log file tail -f /var/log/vmkernel.log Exit from maintenance mode You may be required to refresh the storage adapters after the rescan.

VM disk cannot be resized- Failed to extend the disk Issue:-With the vSphere Client, if you edit a VM's settings and then select one of its virtual disks, the option to resize the disk is greyed out. -When trying to extend the disk using vmkftools for resizing, you will receive the below error: Failed to extend the disk. Failed to lock the file. -When you extend the disk using vsphere client, the change is not getting reflected. Root cause:The VM will be having a snapshot. Because when a snaphot is taken the actual VMDK file will be locked and the changes will be written to a new delta file. Due to this reason, the actual VMDK file could not be resized. Another possible reason: If the disk is IDE, the change may not get reflected. The resolution step for this issue is mentioned here

Resolution:Remove the snapshot file and then try to resize.

Cannot create VMs with virtual machine version 9 in VMware ESXi

One of the main addtion of VMware ESXi 5.1 is the introduction of new VM version (VM version 9).

But when we try to create a new virtual machine using vsphere client 5.1, the option to choose VM version 9 will not be available. This is an intentional omission from VMware. To promote the use of vSphere web client. The new option of VM version 9 is available only in vSphere web client

Issue taking backup of ESXi Configuration Issue:You might have faced the following issue when trying to take a configuration backup of ESXi C:\Program Files\VMware\VMware vSphere CLI>vicfg-cfgbackup.pl -save --server 172.xx.xx.xxx backup.bak Enter username: root Enter password:***** Server version unavailable at 'https://localhost:443/sdk/vimService.wsdl' at C:/Program Files/VMware/VMware vSphere CLI/Perl/lib/VMware/VICommon.pm line 545, line 2.

Resolution:Run the perl.exe and vicfg-cfgbackup.pl from the original location C:\>"C:\Program Files\VMware\VMware vSphere CLI\Perl\bin\perl.exe" "C:\Program Files\VMware\VMware vSphere CLI\bin\esxcfg-cfgbackup.pl" -save --server 172.xx.xx.xx test_bkf.bkf Enter username: root Enter password:******* Saving firmware configuration to test_bkf.bkf ... By default the backup of configuration file will be saved under C:\Users\username\AppData\Local\VirtualStore\Program Files\VMware\VMware vSphere CLI

VMware ESXi host shows disconnected

Symptom: The host and VMs in a vcenter server appears to be disconnected. Issue: The host and its corresponding vms could appear as disconnected due to issue with any of the following services.



vpxa - a service which runs in the esxi host. This service communicates with vcenter server.



hostd - core service which runs in the esxi host



vpxd - a service which runs in the vcenter server which communicates with the vpxa

Resolution:

1. Try to ping the ESXi host. This ensures that the host is reachable 2. Ensure you can login to the VMs remotely. This ensures that VMs in the host are working fine. 3. Try to login to the ESXi host using vsphere client. This ensures that the hostd services are running perfectly. If this step fails, restart the hostd service using putty. 4. If the above three steps worked fine for you, the issue would be with the vpxa or vpxd service. In that case, first try to restart the vpxa service in the host and if that didnot resolve the issue, try restarting vcenter server service of the vcenter.

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1. What is a Hypervisor? It is a program that allows multiple operating systems to share a single hardware host. Each operating system appears to have the host’s processor, memory, and other resources all to itself. However, the hypervisor is actually controlling the host processor and resources, allocating what is needed to each operating system in turn and making sure that the guest operating systems (called virtual machines) cannot disrupt each other. 2. What is the hardware version used in VMware ESXi 5.5? Version 10 Below is the table showing the different version of hardware used in different VMware products along with their release version

Virtual Hardware Version

Products

10

ESXi 5.5, Fusion 6.x, Workstation 10.x, Player 6.x

9

ESXi 5.1, Fusion 5.x, Workstation 9.x, Player 5.x

8

ESXi 5.0, Fusion 4.x, Workstation 8.x, Player 4.x

7

ESXi/ESX 4.x, Fusion 2.x/3.x Workstation 6.5.x/7.x,Player 3.x

6

Workstation 6.0.x

4

ACE 2.x, ESX 3.x, Fusion 1.x, Player 2.x

3 and 4

ACE 1.x, Player 1.x, Server 1.x, Workstation 5.x, Workstation 4.x

3

ESX 2.x, GSX Server 3.x

3. What is the difference between the vSphere ESX and ESXi architectures? VMware ESX and ESXi are both bare metal hypervisor architectures that install directly on the server hardware. Although neither hypervisor architectures relies on an OS for resource management, the vSphere ESX architecture relied on a Linux operating system, called the Console OS (COS) or service console, to perform two management functions: executing scripts and installing third-party agents for hardware monitoring, backup or systems management.

In the vSphere ESXi architecture, the service console has been removed. The smaller code base of vSphere ESXi represents a smaller “attack surface” and less code to patch, improving reliability and security. 4. What is a .vmdk file? This isn’t the file containing the raw data. Instead it is the disk descriptor file which describes the size and geometry of the virtual disk file. This file is in text format and contains the name of the –flat.vmdk file for which it is associated with and also the hard drive adapter type, drive sectors, heads and cylinders, etc. One of these files will exist for each virtual hard drive that is assigned to your virtual machine. You can tell which –flat.vmdk file it is associated with by opening the file and looking at the Extent Description field. Follow the below link for more details VMware files description

5. What are the different types of virtualization? Server Virtualization – consolidating multiple physical servers into virtual servers that run on a single physical server.

Application Virtualization – an application runs on another host from where it is installed in a variety of ways. It could be done by application streaming, desktop virtualization or VDI, or a VM package (like VMware ACE creates with a player). Microsoft Softgrid is an example of Application virtualization. Presentation Virtualization – This is what Citrix Met frame (and the ICA protocol) as well as Microsoft Terminal Services (and RDP) are able to create. With presentation virtualization, an application actually runs on another host and all that you see on the client is the screen from where it is run. Network Virtualization – with network virtualization, the network is “carved up” and can be used for multiple purposes such as running a protocol analyzer inside an Ethernet switch. Components of a virtual network could include NICs, switches, VLANs, network storage devices, virtual network containers, and network media. Storage Virtualization – with storage virtualization, the disk/data storage for your data is consolidated to and managed by a virtual storage system. The servers connected to the storage system aren’t aware of

where the data really is. Storage virtualization is sometimes described as “abstracting the logical storage from the physical storage. 6. What is VMware vMotion and what are its requirements? VMware VMotion enables the live migration of running virtual machines from one physical server to another with zero downtime. VMotion lets you: 

Automatically optimize and allocate entire pools of resources for maximum hardware utilization and



availability.



Perform hardware maintenance without any scheduled downtime.



Proactively migrate virtual machines away from failing or under performing servers.

Below are the pre-requisites for configuring vMotion 

Each host must be correctly licensed for vMotion



Each host must meet shared storage requirements



vMotion migrates the vm from one host to another which is only possible with both the host are sharing a common storage or to any storage accessible by both the source and target hosts.



A shared storage can be on a Fibre Channel storage area network (SAN), or can be implemented using iSCSI SAN and NAS.



If you use vMotion to migrate virtual machines with raw device mapping (RDM) files, make sure to maintain consistent LUN IDs for RDMs across all participating hosts.



Each host must meet the networking requirements



Configure a VMkernel port on each host.



Dedicate at least one GigE adapter for vMotion.



Use at least one 10 GigE adapter if you migrate workloads that have many memory operations.



Use jumbo frames for best vMotion performance.



Ensure that jumbo frames are enabled on all network devices that are on the vMotion path including physical NICs, physical switches and virtual switches.

7. What is the difference between clone and template in VMware? Clone 

A clone is a copy of virtual machine.



You cannot convert back the cloned Virtual Machine.



A Clone of a Virtual Machine can be created when the Virtual Machine is powered on



Cloning can be done in two ways namely Full Clone and Linked Clone.



A full clone is an independent copy of a virtual machine that shares nothing with the parent virtual machine after the cloning operation. Ongoing operation of a full clone is entirely separate from the parent virtual machine.



A linked clone is a copy of a virtual machine that shares virtual disks with the parent virtual machine in an ongoing manner. This conserves disk space, and allows multiple virtual machines to use the same software installation.



Cloning a virtual machine can save time if you are deploying many similar virtual machines. You can create, configure, and install software on a single virtual machine, and then clone it multiple times, rather than creating and configuring each virtual machine individually.

Template 

A template is a master copy or a baseline image of a virtual machine that can be used to create many clones.



Templates cannot be powered on or edited, and are more difficult to alter than ordinary virtual machine.



You can convert the template back to Virtual Machine to update the base template with the latest released patches and updates and to install or upgrade any software and again convert back to template to be used for future deployment of Virtual Machines with the latest patches.



Convert virtual Machine to template cannot be performed, when Virtual machine is powered on. Only Clone to Template can be performed when the Virtual Machine is powered on.



A template offers a more secure way of preserving a virtual machine configuration that you want to deploy many times.



When you clone a virtual machine or deploy a virtual machine from a template, the resulting cloned virtual machine is independent of the original virtual machine or template.

8. What is promiscuous mode in Vmware? 

Promiscuous mode is a security policy which can be defined at the virtual switch or portgroup level



A virtual machine, Service Console or VMkernel network interface in a portgroup which allows use of promiscuous mode can see all network traffic traversing the virtual switch.



If this mode is set to reject, the packets are sent to intended port so that the intended virtual machine will only be able to see the communication.



Example: In case you are using a virtual xp inside any Windows VM. If promiscuous mode is set to reject then the virtual xp won’t be able to connect the network unless promiscuous mode is enabled for the Windows VM.

9. What is the difference between Thick provision Lazy Zeroed, Thick provision Eager Zeroed and Thin provision? Thick Provision Lazy Zeroed 

Creates a virtual disk in a default thick format.



Space required for the virtual disk is allocated when the virtual disk is created.



Data remaining on the physical device is not erased during creation, but is zeroed out on demand at a later time on first write from the virtual machine.



Using the default flat virtual disk format does not zero out or eliminate the possibility of recovering deleted files or restoring old data that might be present on this allocated space.



You cannot convert a flat disk to a thin disk.

Thick Provision Eager Zeroed 

A type of thick virtual disk that supports clustering features such as Fault Tolerance.



Space required for the virtual disk is allocated at creation time.



In contrast to the flat format, the data remaining on the physical device is zeroed out when the virtual disk is created.



It might take much longer to create disks in this format than to create other types of disks.

Thin Provision 

It provides on on-demand allocation of blocks of data.



All the space allocated at the time of creation of virtual disk is not utilized on the hard disk, rather only the size with utilized data is locked and the size increases as the amount of data is increased on the disk.



With thin provisioning, storage capacity utilization efficiency can be automatically driven up towards 100% with very little administrative overhead.

10. What is a snapshot? A snapshot is a “point in time image” of a virtual guest operating system (VM). That snapshot contains an image of the VMs disk, RAM, and devices at the time the snapshot was taken. With the snapshot, you can return the VM to that point in time, whenever you choose. You can take snapshots of your VMs, no

matter what guest OS you have and the snapshot functionality can be used for features like performing image level backups of the VMs without ever shutting them down. 11. What is VDI? 

VDI stands for Virtual Desktop Infrastructure where end user physical machine like desktop or laptop are virtualized due to which VMware described VDI as “delivering desktops from the data center”.



Once VDI is used the end user connect to their desktop using a device called thin client.



The end user can also connect to their desktop using VMware Horizon View installed on any desktop or mobile devices

12. What is VMware HA? 

VMware HA i.e. High Availability which works on the host level and is configured on the Cluster.



A Cluster configured with HA will migrate and restart all the vms running under any of the host in case of any host-level failure automatically to another host under the same cluster.



VMware HA continuously monitors all ESX Server hosts in a cluster and detects failures.



VMware HA agent placed on each host maintains a heartbeat with the other hosts in the cluster using the service console network. Each server sends heartbeats to the others servers in the cluster at five-second intervals. If any servers lose heartbeat over three consecutive heartbeat intervals, VMware HA initiates the failover action of restarting all affected virtual machines on other hosts.



You can set virtual machine restart priority in case of any host failure depending upon the critical nature of the vm.

NOTE: Using HA in case of any host failure with RESTART the vms on different host so the vms state will be interrupted and it is not a live migration 13. What is the difference between VMware HA and vMotion? VMware HA is used in the event when any of the hosts inside a cluster fails then all the virtual machines running under it are restarted on different host in the same cluster. Now HA is completely dependent on vMotion to migrate the vms to different host so vMotion is just used for the migration purpose between multiple hosts. vMotion also has the capability to migrate any vm without interrupting its state to any of the host inside cluster. 14. What is storage vMotion?



Storage vMotion is similar to vMotion in the sense that “something” related to the VM is moved and there is no downtime to the VM guest and end users. However, with SVMotion the VM Guest stays on the server that it resides on but the virtual disk for that VM is what moves.



With Storage vMotion, you can migrate a virtual machine and its disk files from one datastore to another while the virtual machine is running.



You can choose to place the virtual machine and all its disks in a single location, or select separate locations for the virtual machine configuration file and each virtual disk.



During a migration with Storage vMotion, you can transform virtual disks from Thick-Provisioned Lazy Zeroed or Thick-Provisioned Eager Zeroed to Thin-Provisioned or the reverse.



Perform live migration of virtual machine disk files across any Fibre Channel, iSCSI, FCoE and NFS storage

15. What is VMware DRS and how does it works? 

Here DRS stands for Distributed Resource Scheduler which dynamically balances resource across various host under Cluster or resource pool.



VMware DRS allows users to define the rules and policies that decide how virtual machines share resources and how these resources are prioritized among multiple virtual machines.



Resources are allocated to the virtual machine by either migrating it to another server with more available resources or by making more “space” for it on the same server by migrating other virtual machines to different servers.



The live migration of virtual machines to different physical servers is executed completely transparent to end-users through VMware VMotion



VMware DRS can be configured to operate in either automatic or manual mode. In automatic mode, VMware DRS determines the best possible distribution of virtual machines among different physical servers and automatically migrates virtual machines to the most appropriate physical servers. In manual mode, VMware DRS provides a recommendation for optimal placement of virtual machines, and leaves it to the system administrator to decide whether to make the change.

16. What is VMware Fault Tolerance? 

VMware Fault Tolerance provides continuous availability to applications running in a virtual machine, preventing downtime and data loss in the event of server failures.



VMware Fault Tolerance, when enabled for a virtual machine, creates a live shadow instance of the primary, running on another physical server.



The two instances are kept in virtual lockstep with each other using VMware vLockstep technology



The two virtual machines play the exact same set of events, because they get the exact same set of inputs at any given time.



The two virtual machines constantly heartbeat against each other and if either virtual machine instance loses the heartbeat, the other takes over immediately. The heartbeats are very frequent, with millisecond intervals, making the failover instantaneous with no loss of data or state.



VMware Fault Tolerance requires a dedicated network connection, separate from the VMware VMotion network, between the two physical servers.

17. In a cluster with more than 3 hosts, can you tell Fault Tolerance where to put the Fault Tolerance virtual machine or does it chose on its own? You can place the original (or Primary virtual machine). You have full control with DRS or vMotion to assign it to any node. The placement of the Secondary, when created, is automatic based on the available hosts. But when the Secondary is created and placed, you can vMotion it to the preferred host. 18. How many virtual CPUs can I use on a Fault Tolerant virtual machine ? vCenter Server 4.x and vCenter Server 5.x support 1 virtual CPU per protected virtual machine. 19. What happens if vCenter Server is offline when a failover event occurs? When Fault Tolerance is configured for a virtual machine, vCenter Server need not be online for FT to work. Even if vCenter Server is offline, failover still occurs from the Primary to the Secondary virtual machine. Additionally, the spawning of a new Secondary virtual machine also occurs without vCenter Server. 20. What is the difference between Type 1 and Type 2 Hypervisor? Type 1 Hypervisor 

This is also known as Bare Metal or Embedded or Native Hypervisor.



It works directly on the hardware of the host and can monitor operating systems that run above the hypervisor.



It is completely independent from the Operating System.



The hypervisor is small as its main task is sharing and managing hardware resources between different operating systems.



A major advantage is that any problems in one virtual machine or guest operating system do not affect the other guest operating systems running on the hypervisor.



Examples: VMware ESXi Server, Microsoft Hyper-V, Citrix/Xen Server

Type 2 Hypervisor 

This is also known as Hosted Hypervisor.



In this case, the hypervisor is installed on an operating system and then supports other operating systems above it.



It is completely dependent on host Operating System for its operations



While having a base operating system allows better specification of policies, any problems in the base operating system a ffects the entire system as well even if the hypervisor running above the base OS is secure.



Examples: VMware Workstation, Microsoft Virtual PC, Oracle Virtual Box

21. How does vSphere HA works? When we configure multiple hosts for HA cluster, a single host is automatically elected as the master host. The master host communicates with vCenter Server and monitors the state of all protected virtual machines and of the slave hosts. When you add a host to a vSphere HA cluster, an agent is uploaded to the host and configured to communicate with other agents in the cluster. 22. What are the monitoring methods used for vSphere HA? The Master and Slave hosts uses two types of monitoring the status of the hosts 

Datastore Heartbeat



Network Heartbeat

23. What are the roles of master host in vSphere HA? 

Monitoring the state of slave hosts. If a slave host fails or becomes unreachable, the master host identifies which virtual machines need to be restarted.



Monitoring the power state of all protected virtual machines. If one virtual machine fails, the master host ensures that it is restarted. Using a local placement engine, the master host also determines where the restart should be done.



Managing the lists of cluster hosts and protected virtual machines.



Acting as vCenter Server management interface to the cluster and reporting the cluster health state.

24. How is a Master host elected in vSphere HA environment? When vSphere HA is enabled for a cluster, all active hosts (those not in standby or maintenance mode, or not disconnected) participate in an election to choose the cluster’s master host. The host that mounts the

greatest number of datastores has an advantage in the election. Only one master host typically exists per cluster and all other hosts are slave hosts. If the master host fails, is shut down or put in standby mode, or is removed from the cluster a new election is held. 25. If the vCenterserver goes down with a situation that it was pre configured with vSphere HA and DRS, so after power down will HA and DRS perform their task? vSphere HA is not dependent on vCenterserver for its operations as when HA is configured it installs an agent into each host which does its part and is not dependent on vCenterserver. Also HA doesnot uses vMotion, it justs restarts the vms into another host in any case of host failure. Further vSphere DRS is very much dependent on vCenterserver as it uses vMotion for its action for live migration of vms between multiple hosts so in case vCenterserver goes down the vMotion won’t work leading to failure of DRS.

VMware infrastructure become very large day by day and VMware is keep on integrating new technologies to their newer vSphere releases. Its becoming quite difficult for VMware newbies to understand the technology and product completely. This article will answer many questions for VMware beginners about the VMware vSphere product offerings and features.I have not explained the products and features very deeply but this one line answers will help you on interviews to keep your answer short and sweet. 1.What are the products included in VMware vSphere 5.5 Bundle ?  VMware ESXi 

VMware vCenter Server



VMware vSphere Client and Web Client



vSphere Update Manager



VMware vCenter Orchestrator

2.What type of Hyper-visor VMware ESXi is ?  VMware ESXi is Bare-metal hypervisor. You can directly install on server hardware.

VMware Hypervisor 3.What is the role of VMware vCenter server?  vCenter provides a centralized management platform and framework for all ESXi hosts and their respective VMs. vCenter server allows IT administrators to deploy, manage, monitor, automate, and secure a virtual infrastructure in a centralized fashion. To help provide scalability , vCenter Server leverages a back-end database (Microsoft SQL Server and Oracle are both supported, among others) that stores all the data about the hosts and VMs.

vCenter Server – Overview 4. Is it possible install vCenter server on Linux hosts ?



No.But Pre-build vCenter appliance is available in VMware portal which is Linux based.You can import the appliance as virtual machine.

5.How to update the VMware ESXi hosts with latest patches ?  We can update the ESXi hosts using VMware Update Manager(VUM). We can use this VUM add-on package on Windwos based vCenter server and Linux based vCenter server (vCenter appliance) 6.What is the use of VMware vSphere Client and vSphere Web Client ?  vCenter Server provides a centralized management framework to VMware ESXi hosts.To access vCenter server, you need vSphere client or vSphere Web client service enabled.

vSphere Client 7.What is the difference between vSphere Client and vSphere web client ?  vSphere Client is traditional utility which provides user interface to vCenter server. But from VMware vSphere 5 onwards,vSphere web client is a primary interface to manage vCenter server.For vSphere client, you need install small utility .But vSphere Web client doen‟t require any software. You can directly connect using web browser.But still VUM is managed through vSphere Client . vSphere Client:

vSphere Client – Login vSphere web-client:

vSphere web client 8.What is the use of VMware vCenter Orchestrator ?  vCneter Orchestrator is used for automation on various vSphere products.

9.What are the features included in VMware vSphere 5.5 ?  vSphere High Availabitliy (HA) 

vSphere Fault Tolerance



vSphere vMotion



vSphere Storage vMotion



vSphere Distributed Resource Scheduler (DRS)



virtual SAN (VSAN)



Flash Read Cache



Storage I/O Control



Network I/O Control



vSphere Replication

10.What is the use of vSphere High Availability(HA)? Where it can be applied ?  VMware vSphere HA minimize the VM‟s unplanned downtime by restarting the VM guests on next available server ESXi node inacase of failure on current ESXI node. VMware HA must be enabled to reduce the VM unplanned downtime.

VMware HA

11. Will vSphere HA help on VM failures too ?



In an order to detect the VM failures, you need to enable VM Failure Monitoring. So that it detects the Disk I/O and sends the internal heartbeat to check the VM all the time. If the VM is stopped functioning, VM will be restarted automatically by vSphere HA. 12.What is the use of vMotion ?  Using vMotion feature,we can move the running VM‟s from one ESXi host to another ESXi host without any downtime. vMotion copies the VM‟s in-memory contents to the destination server and freeze the operation on current ESXi host and resumes the VM‟s on remote ESXI node.

VMware vMotion 13.What is the use of Storage vMotion ?  vMotion is possible only when you have Shared storage like FC-SAN,ISCSI-SAN or NFS. If you want to move the VM from one datastore to another datastore without any downtime,then you need to perform storage vMotion.

vMotion and Storage vMotion Note: You can perform the vMotion and Storage vMotion together without any downtime. 14.Why vMotion feature is not used/can‟t use in vSphere HA ?  vMotion is used for planned migrations and possible only where the source and destination ESXI hosts are running properly.vSPhere HA is used to reduce the downtime due to failures of physical ESXi hosts.So When the failure accours on ESXi nodes, there is no time to perform vMotion and can‟t be used. 15.Is there any way to prevent the VM‟s unplanned downtime using vSphere HA ?  Yes.You can prevent the unplanned downtime using vSphere falut tollerance along with vSphere HA. 16.How the vSphere Fault tolerance(FT) works ?  Using vLockstep technology , vSphere FT maintains the mirrored secondary VM on different ESXi physical host that is kept in lockstep with the primary.So when the primary ESXi node goes down due to hardware issue, secondary VM will immediately step-in and provide the service. At this point, this VM will become primary and secondary aka mirrored VM will be created on possible ESXI host to prevent the further ESXi failure.

VMware Fault Tolerance (FT) 17.What is vSphere DRS(Distributed Resource Scheduler) ? How it works ?  vSphere DRS is an intelligent frame works which always monitors the cluster nodes health check and performs the vMotion automatically whenever required. For an example ,if one of the ESXI cluster host memory has been utilized more than 90% and due to that lot of paging happening on that server. vSphere DRS detects such things in quick time and moves few VM‟s to another ESXi cluster to least-balance the cluster nodes without any downtime by leveraging vMotion functionality. It applies for high contention for CPU utilization too. So vSphere DRS helps to balance the CPU & Memory utilization across the ESXi cluster nodes.

Vmware DRS 18. What is vSphere storage DRS ? How it works ?



vSphere Storage DRS like vSphere DRS but it applies to storage.It helps to balance storage utilization and performance between data-stores on same ESXi clusters.

`19.What is VSAN ? How it works ?  VSAN forms the storage pools across the multiple nodes using internal disks and allows you to create a datastores that spans multiple ESXI hosts. VSAN also protect the data using VM storage profiles and you can configure it according to your requirement. You need SSD‟s(Solid State Drive) to configure VSAN. Click here to learn more about VSAN.

VSAN overview 20.What is Flash Read Cache ?  vSphere 5.5 supports solid state drive through feature called Flash Read Cache.Using Flash Read Cache, you can assign a caching space to VM‟s like how are you assigning like CPU,Memory and other resources to VM‟s. Solid state drive can provide much better that IOPS compare to normal disks.

Flash Read Cache 21.What is the use of Storage I/O Control in vSphere 5.5 ?  You can limit the number of IOPS for each VM. 22.What is the use of network I/O control ?  Its similar to storage I/O control but its controls the VM‟s Network bandwidth. 23.What is vSphere Replication?  It replicates the complete VM from one datacenter to another datacenter on per VM basis Unlike hardware replication.

vSphere Replication Hope I have mostly covered about all the vSphere products and it features in high level. Share it ! Comment it !! Be Sociable!!!

How to calculate the vSphere’s VM memory usage ? July 30, 2014 in VMware vSphere

To understand, VMware‟s memory management required some sort of skills. Because it had bounded with many technologies like sharing the memory between virtual machines(TPS) , compressing the memory content, Eliminating the duplicate memory content etc…As a Unix/Linux/Windows admin , we can login to guest VM and check the current memory usage at the VM level. But to understand, how the VM is getting the physical memory at the ESXi level , You have to login in to vSphere Client and check the Resource Allocation tab. Most the members get confused after seeing the VM‟s resource allocation tab from vSphere Client. This article is going t0 explain how VMware is calculating the virtual memory and how to find the VM‟s real memory usage. Memory Usage from VM guest Level Login to the guest OS and see how much memory in use .VM- Redhat Linux # top top - 10:45:26 up 243 days, 22:01, Tasks: 143 total, Cpu(s): Mem:

0.1%us,

1 user,

1 running, 142 sleeping, 0.0%sy,

5858188k total,

0.0%ni, 99.8%id,

5792276k used,

load average: 0.02, 0.02, 0.00 0 stopped, 0.0%wa,

0 zombie

65912k free,

0.0%hi,

0.0%si,

245984k buffers

0.0%st

Swap:

2064376k total,

96k used,

2064280k free,

4968504k cached

# free -m total

used

free

shared

buffers

cached

5720

5656

64

0

240

4852

-/+ buffers/cache:

564

5156

0

2015

Mem:

Swap:

2015

#

According to the VM, physical memory is used 5656MB. (5.5GB~) Memory usage from vSphere Client’s Resource allocation tab Login to vSphere Client and Select host and clusters . Just find the VM and select the Resource allocation table.

VMware vSphere Client – VM Memory usage After looking the Resource allocation tab, confusion begins about the VMware memory management. We will see the memory terms in VMware vSphere and how it works ?  What is Guest Memory ? Amount of Memory that you have allocated to the VM.

VM-Physical Memory 

What is Host Memory ? Amount of Memory that you have allocated to the VM + Overhead Memory in approx.(System will take it automatically).This actually refers the random-access memory (RAM) that‟s actually installed in the hardware that comprises the ESX server system. Note : The overhead memory size will be decided by VMkernel. (Here I am not talking about overhead consumption .

Host Memory VS Guest Memory 

What is overhead Memory ? To manage VM , VMware ESXi‟s VMkernel need additional memory space to maintain the virtual hardware. Depends on the VM‟s virtual resources, overhead memory will increase or decrease.

Overhead Consumption 

What is consumed Memory ? The amount of memory space used by the virtual machine. (Private Memory + Overhead Consumption.).In My case ,it was not matching values perfectly because VMware tool is outdated.

Consumed Memory Please go through this article to know more about Shared,Swapped,Compresses and Ballooned Memory.  What is private Memory ? The amount of memory that has been committed to the VM at that time.  What is shared Memory ? Memory that has been provided by TPS. (Transparent Page Sharing)  What is Swapped Memory ? VM‟s low priority pages that has been swapped by ESXi host. (Moving the physical Memory contents to the disk.)  What is Compressed Memory ? The swapped pages can be compressed by 50% ratio using memory compression technology. Amount of compressed Memory.  What is Ballooned ? Amount of Memory reclaimed by the balloon driver.  What is Un-Accessed ? The amount of memory that has been untouched by VM.  What is Active ? The Amount of memory that has been recently used. (Read/Write). The conclusion is that VM‟s memory usage(5.5GB~) is matching to the consumed memory in vSphere Client. (5.49GB~).So you no need to calculate other fields value. Summary: Field

Description

Private

Amount of memory backed by host memory and not being shared.

Shared

Amount of memory being shared.

Swapped

Amount of memory reclaimed by swapping.

Compressed

Amount of memory stored in the virtual machine’s compression cache.

Ballooned

Amount of memory reclaimed by ballooning.

Unaccessed

Amount of memory never referenced by the guest.

Active

Amount of memory recently accessed.

Hope this article provides some idea about VMware memory management. We will see the Guest Memory in details in upcoming article.

Dynamically Adding Memory CPU to VM on VMware 26 days ago in VMware vSphere, VMware-Guests

VMware vSphere‟s hot-add Memory and hot-plug CPU functions allow you to add the CPU and Memory while virtual machine is up and running. It will help you to add the additional resources whenever required and no need to bring down the VM for each time.But you can‟t remove the resources once you have added the VM while its running.This Hot-add RAM and Hot-plug CPU will work on specific version of windows server operating systems.(Windows Server 2008 ) I have tested this features on Redhat Enterprise Linux 6.3 and it works like charm. These featutures are heavily depends on the guest operating systems kernel and most of the Unix Like operating system‟s kernel can recognize the hardware changes quickly and it will start using it. Enterprise Operating systems like Oracle Solaris , IBM AIX and HP-UX supports these features from over the decade with help of their own RISC architecture hardwares. In this article ,we will see that how we can enable the hot-plug CPU and Hot-add RAM on existing VM .

Enabling the VMware vSphere Hot-plug CPU & Hot-Add RAM Feature 1. Login to the VMware vSphere Client and Halt the VM .

Halt the VM 2.Right click the VM and edit the virtual machine settings.

Edit the VM Settings 3.Expand the CPU tab like below.

Expand the CPU 4.Navigate to CPU hot Plug option .

CPU Hot Plug Option 5.Select the “Enable CPU Hot Add” Box.

Check the Enable CPU Hot Add 6.Same way you can configure for memory as well. Just enable the Memory Hot plug like below. So that you can add the memory to the virtual machine while its running.

Enable the Memory Hot Plug 7.Once you have done the above settings just power on the system. Now your VM can support the Hot-plug CPU & Hot-Add RAM features of VMware vSphere.

Power On the VM

Testing the VMware vSphere Hot-plug CPU & Hot-Add RAM 1.Login the VM and check the current CPU & Memory information.(RHEL 6) CPU: [root@UAWEB1 ~]# lscpu Architecture:

x86_64

CPU op-mode(s):

32-bit, 64-bit

Byte Order:

Little Endian

CPU(s):

1

On-line CPU(s) list:

0

Thread(s) per core:

1

Core(s) per socket:

1

CPU socket(s):

1

NUMA node(s):

1

Vendor ID:

GenuineIntel

CPU family:

6

Model:

58

Stepping:

9

CPU MHz:

2893.459

BogoMIPS:

5786.91

L1d cache:

32K

L1i cache:

32K

L2 cache:

256K

L3 cache:

3072K

NUMA node0 CPU(s):

0

[root@UAWEB1 ~]#

Memory: [root@UAWEB1 ~]# free -m total

used

free

shared

buffers

cached

1869

211

1658

0

11

74

-/+ buffers/cache:

125

1744

0

4031

Mem:

Swap:

4031

[root@UAWEB1 ~]#

2.Go Back to VMware vSphere Client console and edit the virtual Machine to increase the memory.(Increased from 2048 to 2560).Click OK to save the settings.

Increase the Memory while system is running 3.Execute the below command on VM guest to see whether newly added memory is reflecting or not. [root@UAWEB1 ~]# free -m total

used

free

shared

buffers

cached

2381

221

2160

0

11

74

-/+ buffers/cache:

135

2246

0

4031

Mem:

Swap:

4031

[root@UAWEB1 ~]#

We can see that total memory has been increased 500MB. Which means Hot RAM feature is working fine on RHEL 6.x 4.Let me increase the number of virtual CPU for the VM guest.

Add additional CPU to the VM while running 5.Check on the CPU information on RHEL VM. [root@UAWEB1 ~]# lscpu Architecture:

x86_64

CPU op-mode(s):

32-bit, 64-bit

Byte Order:

Little Endian

CPU(s):

2

On-line CPU(s) list:

0,1

Thread(s) per core:

1

Core(s) per socket:

1

CPU socket(s):

2

NUMA node(s):

1

Vendor ID:

GenuineIntel

CPU family:

6

Model:

58

Stepping:

9

CPU MHz:

2893.459

BogoMIPS:

5786.91

L1d cache:

32K

L1i cache:

32K

L2 cache:

256K

L3 cache:

3072K

NUMA node0 CPU(s):

0,1

[root@UAWEB1 ~]#

We can see that CPU(s) count has been increased from 1 to 2. Why VMware is not enabling the Hot Memory & Hot CPU feature by default ? There is an little overhead by enabling the features. That‟s why customers need to decides whether they require this feature or not.

How VMware vSphere is saving physical memory ? July 31, 2014 in VMware vSphere, VMware-Guests, vSphere Q&A

There are lot of discussions is going on the blogs,social media‟s about the vSphere‟s VM memory management. So i had just came up with VM‟s memory analysis on the last article. But i haven‟t explained the memory saving techniques on that article. Here we are going to discuss about that. If you look at the vSphere client‟s resource allocation tab, You can see field called “shared” “swapped” “Compressed” “Ballooned” under Guest memory. These are the memory saving techniques which will rescue the system when you have memory over-commit on the ESXi.

VM‟s Memory usage > What is Over-committed memory ? For an example, ESXi physical server is having 64GB RAM and configuring 9 VM‟s with 8GB memory is over-committed .

Memory Overcommit on ESXi  ESXi‟s Physical Memory: 64GB  VM‟s Allocated Memory: 9x8GB = 72GB. When the all VM‟s are start utilizing it‟s full memory quota, VM‟s may crash since you have only 64GB RAM but trying to access 72GB on that ESXi host. To avoid these kind of situation, VM kernel will initiate various memory saving technique to avoid the VM crash. > What is shared ? (See the first image) What is TPS (Transparent Page Sharing) ? How it works ? Shared is amount of memory that has been shared across other VM‟s using TPS (Transparent Page Sharing) mechanism. Hope you have heard about the deduplication on the storage. In storage, deduplication is the process to eliminate the duplicate copies of data using some check-sum mechanism. Same sense has been applied for Memory here.Its just eliminates the duplicate memory contents at ESXi level.

TPS – VMware In one ESXi host , you may run many similar VM‟s (Ex: 10 Redhat Linux 6.5 VM‟s). So the VM‟s memory pages will be same(Some part) as other VM since you have the same operating system installed on those. VMkernel will scan the host‟s physical memory periodically and find the duplicate pages.It just removes the duplicate pages when the host system to run on low memory. The default page size will be 4k .Some of the new VM guests will use 2MB page size ,but you will get

less duplicate pages since 2MB page is huge to match with other. But TPS will think more than us and it will break the 2MB page as 4k chunks and eliminates the duplicate. > What is swapped ? How it works ? This is traditional swapping mechanism which works in ESXi level. When the ESXi is running out of physical memory, It will start move the VM‟s low priority pages to the disks.(Inactive memory). When the VM requires these pages , ESXi will bring it back to memory for use.This swapping will impact the VM‟s performance. So its better to use the Guest level swapping. > What is Compressed? How it works ? ESXi provides the memory compression cache to boost the VM performance during the memory over-commitment. When the memory is over-committed, VMkernel will compress the VM‟s low priority pages and stored in memory.

Memory Compression – Vmware Compression provides better performance than swapping since the contents are retrieved from the memory where as swapping needs to be read from the disk. > What is Ballooned ? How it works ? Memory ballooning is one of the great memory reclaim method to overcome the memory overcommitment. All the VM‟s may not use its full memory quota but application/DB require that amount of memory for that VM during the peak time. VMware ESXi can reclaim the un-used memory during the memory over-commitment with help of ballooning the driver. Ballooning driver will communicate with VM‟s using vmware tools when the memory pressure is increased and reclaims the memory pages which are used in VM. Note: You should maintain the VMware tools up to date on the VM guests in an order to leverage these features.