VMWARE INTERVIEW QUESTIONS
1. What is virtualization? - answer-Virtualization is the creation of a virtual (rather than
actual) version of something, such as an operating system, a server, a storage device or
network resources.
2. What is a Hypervisor? - answer-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
3. What is the difference between Esx and Esxi? - answer-ESX (Elastic Sky X) is the
VMware's flagship enterprise server virtualization platform. In ESX, VMkernel is the
virtualization kernel which is managed by a console operating system which is also called
as Service console. Which is linux based and its main purpose is it to provide a
Management interface for the host and lot of management agents and other thrid party
software agents are installed on the service console to provide the functionalists like
hardware management and monitoring of ESX hypervisor.
ESXi (Elastic sky X Integrated) is also the VMware's flagship enterprise server virtualization
platform. In ESXi, Service console is removed. All the VMware related agents and third
party agents such as management and monitoring agents can also run directly on the
VMkernel. ESXi is ultra-thin architecture which is highly reliable and its small code-base
allows it to be more secure with less codes to patch. ESXi uses Direct Console User
Interface (DCUI) instead of a service console to perform management of ESXi server. ESXi
installation will happen very quickly as compared to ESX installation. ESX 4.1 is the last
version availability of ESX server. After vSphere 5, only ESXi is available.
4. Difference between ESX and GSX? - answer-With VMware Workstation and GSX Server,
the software sits on top of a host operating system such as Windows or Linux. With ESX
Server, the software runs directly on the system's hardware, eliminating the need to install a
base OS. In fact, ESX has its own OS
5. What is VMware vMotion and what are its requirements? - answer-VMware VMotion
enables the live migration of running virtual machines from one physical server to another
with zero downtime, continuous service availability, and complete transaction integrity.
Without share storage you can do VM migration with vMotion and Storage VMotion from
one physical host to another but the virtual machine have to be powered off. Note : Local
storage vMotion needs VM's powered off and share storage vMotion is live migration where
VM's can be powered on.
,Below are the pre-requisites for configuring vMotion
Lisence required vsphere essential plus, standard, enterprise or enterprise plus
Storage requirements: shared storage iSCSI SAN, FC SAN and NAS
VMkernel Management Network should have vMotion Enable
Vswitch have the same name
CPU Compatibility
Support 1GoE 16 NIC Cards or 10 GoE 4 NICs
6. What is VMware HA? - answer-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
Why do you need high availability HA? - answer-Quickly bring backup critical business
applications in the event of an ESXi server failure
Decries downtime and improve availability
Example of business critical application like exchange/email, SQL server/database and
corporate file server
7. What is the difference between VMware HA and vMotion? - answer-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.
8. What is storage vMotion? - answer-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
9. What is VMware DRS and how does it works? - answer-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.
1. What is virtualization? - answer-Virtualization is the creation of a virtual (rather than
actual) version of something, such as an operating system, a server, a storage device or
network resources.
2. What is a Hypervisor? - answer-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
3. What is the difference between Esx and Esxi? - answer-ESX (Elastic Sky X) is the
VMware's flagship enterprise server virtualization platform. In ESX, VMkernel is the
virtualization kernel which is managed by a console operating system which is also called
as Service console. Which is linux based and its main purpose is it to provide a
Management interface for the host and lot of management agents and other thrid party
software agents are installed on the service console to provide the functionalists like
hardware management and monitoring of ESX hypervisor.
ESXi (Elastic sky X Integrated) is also the VMware's flagship enterprise server virtualization
platform. In ESXi, Service console is removed. All the VMware related agents and third
party agents such as management and monitoring agents can also run directly on the
VMkernel. ESXi is ultra-thin architecture which is highly reliable and its small code-base
allows it to be more secure with less codes to patch. ESXi uses Direct Console User
Interface (DCUI) instead of a service console to perform management of ESXi server. ESXi
installation will happen very quickly as compared to ESX installation. ESX 4.1 is the last
version availability of ESX server. After vSphere 5, only ESXi is available.
4. Difference between ESX and GSX? - answer-With VMware Workstation and GSX Server,
the software sits on top of a host operating system such as Windows or Linux. With ESX
Server, the software runs directly on the system's hardware, eliminating the need to install a
base OS. In fact, ESX has its own OS
5. What is VMware vMotion and what are its requirements? - answer-VMware VMotion
enables the live migration of running virtual machines from one physical server to another
with zero downtime, continuous service availability, and complete transaction integrity.
Without share storage you can do VM migration with vMotion and Storage VMotion from
one physical host to another but the virtual machine have to be powered off. Note : Local
storage vMotion needs VM's powered off and share storage vMotion is live migration where
VM's can be powered on.
,Below are the pre-requisites for configuring vMotion
Lisence required vsphere essential plus, standard, enterprise or enterprise plus
Storage requirements: shared storage iSCSI SAN, FC SAN and NAS
VMkernel Management Network should have vMotion Enable
Vswitch have the same name
CPU Compatibility
Support 1GoE 16 NIC Cards or 10 GoE 4 NICs
6. What is VMware HA? - answer-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
Why do you need high availability HA? - answer-Quickly bring backup critical business
applications in the event of an ESXi server failure
Decries downtime and improve availability
Example of business critical application like exchange/email, SQL server/database and
corporate file server
7. What is the difference between VMware HA and vMotion? - answer-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.
8. What is storage vMotion? - answer-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
9. What is VMware DRS and how does it works? - answer-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.
