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
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 dependent on vMotion to perform live migration of the
vms to different host so vMotion is just used for the migration purpose between
multiple hosts which is also used by other functionality like DRS.
NOTE: Anyhow HA can work very will without vMotion as its primary
functionality is to restart the vm from the affected host to the working host
but this will be service affecting as the vms will be 'powered off' and then
'powered on' on the new host.
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
1.
This is also known as Bare Metal or Embedded or Native Hypervisor.
2.
It works directly on the hardware of the host and can monitor
operating systems that run above the hypervisor.
3.
It is completely independent from the Operating System.
4.
The hypervisor is small as its main task is sharing and managing
hardware resources between different operating systems.
5.
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.
6.
Examples: VMware ESXi Server, Microsoft Hyper-V, Citrix/Xen Server
Type 2 Hypervisor
1.
This is also known as Hosted Hypervisor.
2.
In this case, the hypervisor is installed on an operating system
and then supports other operating systems above it.
3.
It is completely dependent on host Operating System for its
operations
4.
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.
5.
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.
26. What is the use of vmware tools?
VMware Tools is a suite of utilities that enhances the performance of the
virtual machine's guest operating system and improves management of the virtual
machine. Without VMware Tools installed in your guest operating system, guest
performance lacks important functionality. Installing VMware Tools eliminates
or improves these issues:
·
Low video resolution
·
Inadequate color depth
·
Incorrect display of network speed
·
Restricted movement of the mouse
·
Inability to copy and paste and drag-and-drop files
·
Missing sound
·
Provides the ability to take quiesced snapshots of the guest OS
·
Synchronizes the time in the guest operating system with the time
on the host
·
Provides support for guest-bound calls created with the VMware VIX
API
