VMware Interview Questions — Part 1

I feel strong need of sharing some questions related to VMware interview. I interact with number of my colleagues and friends (VMware certified Professionals) those who are having experience of sitting on both side of desk.

High Availability

Q : Explain briefly VMware HA ?

A : VMware HA provides high availability to VMs running VMware environment. It helps to minimize the downtime associated with VM.

Q : What are the pre-requisite for HA to work ?

A : Need at least two nodes for HA cluster.
All hosts must have the licensed vSphere HA.
All hosts should have the access to same VM network.

Two datastores for heartbeating (Not mandatory but strongly recommended by VMware)

Q : What are the best practices for VSphere HA cluster ?

A : Setting alarms to monitor the cluster changes.
Monitor cluster validity — In invalid cluster admission control policy is violated.
vSphere HA and storage vMotion Inter-portability in mixed cluster — the cluster consists of different version of ESXi.
NIC which are used for heartbeat its always recommended to put them in Teaming.

Q : What are the admission control best practices ?

A : Select the percentage of cluster resources reserved for admission control policy.

If we are specifying the fail over host policy decide how many hosts are reserved for fail over

Ensure that we all hosts in cluster are having equal resources.

Take into consideration max Memory and max number of vCPU assigned to VM for proper calculation of Slot size.

Fault Tolerance

Q : Explain briefly VMware FT technology ?

A : VMware FT helps to avoid the downtime of VM when our ESX host is getting down. Because two VMs in continous sync are running simultaneously on different ESX hosts.

Q : What is the name of technology used by VMware Fault tolerance?

A : FT is using vLockstep technology.

Q : What is the difference between VMware FT and VMware HA ?

A : VMware FT is used at VM level but HA is used at cluster level both are used to provide
redundancy to VM. In case of FT there is no downtime occur for VM because two VMs are running on
different ESXi hosts but in case of HA same VM is getting failover from one ESX host to another there is downtime coming into picture.

Q : What are the prerequisites to enable VMware FT ?

A : 3 HA enabled hosts are recommended by VMware to enable the FT it can be enabled with 2 hosts but that is not recommended.
vmkernel port enabled with FT traffic should be enabled.
FT enabled VMs should be placed in shared storage.

Q : What are the limitations associated with enabling VMware FT ?

A : FT protected machines require eager zeroed thick disk .
FT enabled VM can’t be storage vmotioned. We have to disable the FT to perform the storage VMotion.
VM HW version should be 7 or above that.
NPIV (Network Port ID virtualization) is not supported.
pRDM (Physical RDM) is not supported but we can give vRDM (Virtual RDM)
Only VM with one vCPU can be part of FT.

Q : How you you visually see the difference between FT enabled VM and simple VM ?

A : FT enabled primary VM will show in dark blew color in VCenter server.


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