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VMware FAQ
1. What is Cloud Computing?
Cloud computing is a style of computing that enables on-demand
network access to a shared
pool of scalable and elastic infrastructure resources. The term
cloud computing originates
from the standard network diagram where a cloud is used to
represent the abstraction of a
complex networked system such as the Internet.
Cloud computing is a type of computing that relies on sharing
computing resources rather
than having local servers or personal devices to handle
applications.
In cloud computing, the word cloud (also phrased as "the cloud")
is used as a metaphor for
"the Internet," so the phrase cloud computing means "a type of
Internet-based computing,"
where different services -- such as servers, storage and
applications -- are delivered to an
organization's computers and devices through the Internet.
Cloud computing builds on virtualization to create a
service-oriented computing model. This
is done through the addition of resource abstractions and
controls to create dynamic pools of
resources that can be consumed through the network. Benefits
include economies of scale,
elastic resources, self-service provisioning, and cost
transparency.
2. What is Virtualization?
Virtualization is the creation of a virtual (rather than actual)
version of IT resources, such as
a hardware platform, operating system (OS), storage device, or
network resources.
3. What is the difference between Virtualization and Cloud
Computing?
Virtualization is the creation of a virtual (rather than actual)
version of something, such as a
hardware platform, an operating system, a storage device or a
network resource. Simply
stated, Virtualization is a technique that allows you to run
more than one server (or another
infrastructure component) on the same hardware. For example, one
server is the host server
and controls the access to the physical servers resources. One
or more virtual servers then
run within containers provided by the host server.
The hypervisor software (which controls access to the physical
hardware) may run on bare
metal allowing a user to run multiple operating systems on the
same physical hardware, or
the hypervisor may run on top of a host operating system,
allowing other operating systems
to run within this host OS, and so on the same physical
hardware. The latter inherently gives
lower performance, since it has to go through more layers of
software to access the physical
resources.
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Cloud Computing is the delivery of computing as a service rather
than a product, whereby
shared resources, software, and information are provided to
computers and other devices as a
metered service over a network (typically the Internet). Cloud
Computing may look like
Virtualization because it appears that your application is
running on a virtual server detached
from any reliance or connection to a single physical host.
However, Cloud Computing can be
better described as a service where Virtualization is part of a
physical infrastructure.
Cloud Computing builds on top of a virtualized infrastructure
(compute, storage, network) by
using standardization and automated delivery to provide service
management. This makes
monitoring the virtualized resources and the responsible
deployment of these resources
possible.
Virtualization is simply a preparation for the delivery of IT in
a very powerful way within an
organization. It removes a level of complexity for end users,
one that should never have been
there in the first place, while primarily cutting costs for the
organization. Cloud Computing
ties directly to the way an organization uses its IT resources
and enables a quantum change in
the experience throughout the organization easing the
administrative burden of deploying,
managing, delivering IT resources, and providing the ability for
end users to request and use
virtualized IT resources (or perhaps even an application or a
business process where the end
user does not have to be aware of the underlying IT resources
being used).
4. Why Virtualize?
There seems to be a bit of confusion about the benefits of
server virtualization, with many
tending to focus on cost savings. As a district that has been
running a virtual infrastructure
for some time, I can honestly say that virtualization is not so
much about saving money
(although you certainly will) as it is about better resource
utilization, more reliability, and
greater flexibility.
Better resource utilization
There is no question that most of our servers are doing nothing
about 90% of the time. This
becomes quite obvious with even a cursory glance at historical
utilization data for any given
server. It would seem that the obvious solution for this would
be to simply run more
applications on each one, but the reality of this is that the
more apps you install on one OS,
the more unreliable it becomes (especially if it's a Microsoft
product.) So, what we all do
instead is buy a new machine every time we want a new app that
we think is "critical,"
because we want to be sure it has its own sandbox to play
in.
So, we find ourselves with racks and racks of servers consuming
more and more space (at a
cost,) all generating heat which we must cool (at a cost,) all
pulling more and more power (at
a cost,) all requiring more and more time to manage (at a
cost.)
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Virtualization offers a way to safely put more than one
operating system (or virtual server)
on one piece of hardware by isolating each operating system from
any others running on the
box. Essentially, you are establishing a bunch of sandboxes on
one piece of hardware. If one
of the virtual servers crashes, hard or soft, it will have no
impact on any of the others on the
box. Hardware resources are better used since, rather than
having 10 independent servers
running at 10 percent utilization each, you can have 2 running 5
virtual servers each for a
total of 50 percent utilization per box. Better still, if
designed properly (more on that later,)
should a virtual server require more resources, it can easily
and instantly be moved to a
machine that offers more, often live and transparently to its
end users.
More reliability
It's important to note, before any discussion on reliability
comes into play, that a virtualized
operating system is, by nature, relatively hardware agnostic.
This means that it (its image,
which is) can easily be moved from one piece of hardware to
another, even if that hardware
is of completely different design, without modification and
often without shutting the system
down (i.e. live migration.) This can dramatically reduce the
time required to bring a failed
system back up, as the typical 2-4 hour OS reinstall phase can
be eliminated.
However, virtualization, by its very design, dramatically
increases the impact of a single
system failure, as a variety of services will be impacted when
multiple virtual servers go
down simultaneously. This is where the "designed properly" comes
into play.
Properly designed, virtualized infrastructure can provide far
greater reliability and less down
time than an infrastructure of individual machines could ever
achieve. The keys to the design
are redundancy and shared storage. All individual pieces of
server hardware must be
redundantly linked to a properly designed SAN or other shared
storage device, where all
virtual machine images are stored for a user to realize the true
reliability benefits of server
virtualization.
Greater flexibility
Finally, and perhaps most importantly, virtualization provides
flexibility, or what I like to
call, an agile infrastructure. I've already described some of
that flexibility in the reliability
section - moving virtual machines live from box to box. Imagine,
for example that one of
your virtual machines is consuming too many resources on the box
it's on, lets say processor
time. People are complaining that things are slowing down. You
say, "no problem," and
move the virtual machine to a box with a free processor. Or, you
take advantage of virtual
smp, and simply pin another processor to the virtual machine.
Ever needed to add more RAM
to a server because a process has outgrown its allocation? No
problem - simply allocate more
RAM to the process. No pulling the server, no extended periods
of down time.
Deployments are equally easy. Once you have one image of an OS,
you know that it will
work on any hardware, so you never have to sit and watch an
installer run, followed by
endless online updates again. Simply copy the image and fire it
up - you're ready to install
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that new app in less than 5 minutes. How much are you paying
people to do this sort of thing,
when they could be working on more important things, like
innovating!
5. What is Hypervisor?
A hypervisor, also called a virtual machine manager, 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 a resource,
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.
6. What is VMware HA?
VMware vSphere High Availability (HA) provides easy-to-use, cost
effective high
availability for applications running in virtual machines. In
the event of physical server
failure, affected virtual machines are automatically restarted
on other production servers with
spare capacity. In the case of operating system failure, vSphere
HA restarts the affected
virtual machine on the same physical server.
With 2 ESX Servers, a SAN for shared storage, Virtual Center,
and a VMHA license, if a
single ESX Server fails, the virtual guests on that server will
move over to the other server
and restart, within seconds. This feature works regardless of
the operating system used or if
the applications support it.
7. How VMware HA works?
VMware HA continuously monitors all virtualized servers in a
resource pool and detects
physical server and operating system failures. To monitor
physical servers, an agent on each
server maintains a heartbeat with the other servers in the
resource pool such that a loss of
heartbeat automatically initiates the restart of all affected
virtual machines on other servers in
the cluster.
VMware HA leverages shared storage and, for FibreChannel and
iSCSI SAN storage, the
VMware vStorage Virtual Machine File System (VMFS) to enable the
other servers in the
cluster to safely access the virtual machine for failover. When
used with VMware Distributed
Resource Scheduler (DRS), VMware HA automates the optimal
placement of virtual
machines on other servers in the cluster after server
failure.
To monitor operating system failures, VMware HA monitors
heartbeat information provided
by the VMware Tools package installed in each virtual machine in
the VMware HA cluster.
Failures are detected when no heartbeat is received from a given
virtual machine within a
user-specified time interval.
VMware HA ensures that sufficient resources are available in the
resource pool at all times to
be able to restart virtual machines on different physical
servers in the event of server failure.
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VMware HA is easily configured for a cluster through VMware
vCenter Server.
8. How to get the HA Status?
Go to the summary tab of your cluster and click Cluster
Status.
Because vCenter Server 5.0 uses Fault Domain Manager (FDM)
agents for High Availability
(HA), rather than Automated Availability Manager (AAM) agents,
the troubleshooting process
has changed.
There are other architectural and feature differences that also
affect the troubleshooting process:
One main log file (/var/log/fdm.log) and syslog integration
Datastore Heartbeat
Reduced Cluster configuration (approximately 1 minute, as
opposed to 1 minute per host)
FDM does not require that DNS be configured on the hosts, nor
does FDM rely on other
Layer 3 to 7 network services
9. What is a Slot?
A slot is a logical representation of the memory and CPU
resources that satisfy the
requirements for any powered-on virtual machine in the cluster.
In other words a slot size is
the worst case CPU and Memory reservation scenario in a
cluster.
10. Where is HA configuration and log file in vSphere 4.1?
1. To check the current installed version of HA agent....run
rpm -qa |grep aam
2. HA agent is installed under
/opt/vmware/aam
3. To check HA nodes log..run
less /var/log/vmware/aam/aam_config_util_listnodes.log
4. To check HA agent log...run
less /var/log/vmware/aam/agent/run.log
5. To check HA install and current configuration log.....run
less /var/log/vmware/aam/aam_config_util_install.log
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11. Where is HA configuration and log file in vSphere 5.0?
/var/log/fdm.log
12. What is AAM in HA?
AAM is the Legato automated availability management. Prior to
vSphere 4.1, VMware's HA
is actually re-engineered to work with VM's with the help of
Legatos Automated Availability Manager (AAM) software. VMware's
vCenter agent (vpxa) interfaces with the
VMware HA agent which acts as an intermediary to the AAM
software. From vSphere 5.0, it
uses an agent called FDM (Fault Domain Manager).
13. What is Fault Domain Manager?
In and among all its new features, vSphere 5.0 introduces a
complete rewrite of vSphere HA
clustering. Replacing its earlier technology for vSphere HA
(AAM) is a new host agent
called the Fault Domain Manager, or FDM. This agent is
responsible for monitoring host
availability and the power state of protected VMs, with the
mission of restarting
protected VMs when a host or VM fails.
14. What are prerequisites for VMware HA to work?
Shared storage for the VMs running in HA cluster
Essentials plus, Standard, Advanced, Enterprise and Enterprise
Plus Licensing
VMHA enabled Cluster
At least two shared heartbeat data stores between the hosts in
VMware HA cluster
Management network redundancy to avoid frequent isolation
response in case of temporary network issues (preferred not a
requirement)
15. What is the maximum number of hosts supported per HA
cluster?
Maximum number of hosts in the HA/DRS cluster is 32
16. What is VMware DRS?
VMware DRS (Distributed Resource Scheduler) is a utility that
balances computing
workloads with available resources in a virtualized environment.
VMware DRS
dynamically balances computing capacity across a collection of
hardware resources
aggregated into logical resource pools, continuously monitoring
utilization across resource
pools and intelligently allocating available resources among the
virtual machines based on
pre-defined rules that reflect business needs and changing
priorities. When a virtual machine
experiences an increased load, VMware DRS automatically
allocates additional resources by
redistributing virtual machines among the physical servers in
the resource pool.
With VMware DRS, users define the rules for allocation of
physical resources among virtual
machines. The utility can be configured for manual or automatic
control. Resource pools can
be easily added, removed or reorganized. If desired, resource
pools can be isolated between
different business units. If the workload on one or more virtual
machines drastically changes,
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VMware DRS redistributes the virtual machines among the physical
servers. If the overall
workload decreases, some of the physical servers can be
temporarily powered-down and the
workload consolidated.
Other features of VMware DRS include:
Dedicated infrastructures for individual business units
Centralized control of hardware parameters
Continuous monitoring of hardware utilization
Optimization of the use of hardware resources as conditions
change
Prioritization of resources according to application
importance
Downtime-free server maintenance
Optimization of energy efficiency
Reduction of cooling costs.
17. What is VMware DPM?
VMware Distributed Power Management (DPM) is a pioneering new
feature of VMware
DRS that continuously monitors resource requirements in a VMware
DRS cluster. When
resource requirements of the cluster decrease during periods of
low usage, VMware DPM
consolidates workloads to reduce power consumption by the
cluster. When resource
requirements of workloads increase during periods of higher
usage, VMware DPM brings
powered-down hosts back online to ensure service levels are
met.
VMware DPM allows IT organizations to:
Cut power and cooling costs in the datacenter Automate
management of energy efficiency in the datacenter
18. How Does VMware DRS Work?
VMware DRS allocates and balances resources in a DRS cluster. It
does this dynamically
and continuously monitors for changes in utilization.
Resource pools are used to allocate resources to a set of
virtual machines in a DRS cluster.
When load increases in a VM, DRS will redistribute VMs to other
physical servers if
required to ensure all VMs get their correct share of
resources.
When a VM is powered on DRS is used to decide which server it is
best to be placed on.
If a VM is running and DRS decides that it needs to be placed on
another physical server to
ensure its requirements are met, vMotion is used.
This allows the VM to be moved without powering it off or loss
of service, allowing
resources to be balanced.
19. What are the requirements for FT?
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Here are the requirements for the host.
The vLockstep technology used by FT requires the physical
processor extensions added
to the latest processors from Intel and AMD. In order to run FT,
a host must have an FT-
capable processor, and both hosts running an FT VM pair must be
in the same processor
family.
CPU clock speeds between the two hosts must be within 400MHz of
each other to ensure
that the hosts can stay in sync.
All hosts must be running the same build of ESX or ESXi and be
licensed for FT,
which is only included in the Advanced, Enterprise, and
Enterprise Plus editions of
vSphere.
Hosts used together as an FT cluster must share storage for the
protected VMs (FC,
iSCSI, or NAS).
Hosts must be in an HA-enabled cluster.
Network and storage redundancy is recommended to improve
reliability; use NIC
teaming and storage multipathing for maximum reliability.
Each host must have a dedicated NIC for FT logging and one for
VMotion with speeds
of at least 1Gbps. Each NIC must also be on the same
network.
Host certificate checking must be enabled in vCenter Server
(configured in vCenter
Server Settings SSL Settings).
Here are the requirements for the VMs.
The VMs must be single-processor (no vSMPs).
All VM disks must be "thick" (fully allocated) and not "thin."
If a VM has a thin disk, it
will be converted to thick when FT is enabled.
There can be no nonreplayable devices (USB devices,
serial/parallel ports, sound cards, a
physical CD-ROM, a physical floppy drive, physical RDMs) on the
VM.
Most guest OSs are supported, with the following exceptions that
apply only to hosts
with third-generation AMD Opteron processors (i.e., Barcelona,
Budapest, Shanghai):
Windows XP (32-bit), Windows 2000, and Solaris 10 (32-bit)..
In addition to these requirements, there are also many
limitations when using FT, and they
are as follows.
Snapshots must be removed before FT can be enabled on a VM. In
addition, it is not
possible to take snapshots of VMs on which FT is enabled.
N_Port ID Virtualization (NPIV) is not supported with FT. To use
FT with a VM you
must disable the NPIV configuration.
Paravirtualized adapters are not supported with FT.
Physical RDM is not supported with FT. You may only use virtual
RDMs.
FT is not supported with VMs that have CD-ROM or floppy virtual
devices connected to
a physical or remote device. To use FT with a VM with this
issue, remove the CD-ROM
or floppy virtual device or reconfigure the backing with an ISO
installed on shared
storage.
The hot-plug feature is automatically disabled for fault
tolerant VMs. To hot-plug devices
(when either adding or removing them), you must momentarily turn
off FT, perform the
hot plug, and then turn FT back on.
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EPT/RVI is automatically disabled for VMs with FT turned on.
IPv6 is not supported; you must use IPv4 addresses with FT.
VMotion is supported on FT-enabled VMs, but you cannot VMotion
both the primary
and secondary VMs at the same time. SVMotion is not supported on
FT-enabled VMs.
In vSphere 4.0, FT was compatible with DRS, but the automation
level was disabled for
FT-enabled VMs. Starting in vSphere 4.1, you can use FT with DRS
when the EVC
feature is enabled. DRS will perform initial placement on
FT-enabled VMs and also will
include them in the cluster's load-balancing calculations. If
EVC in the cluster is disabled,
the FT-enabled VMs are given a DRS automation level of
"disabled". When a primary
VM is powered on, its secondary VM is automatically placed, and
neither VM is moved
for load-balancing purposes.
20. What are prerequisites for VMware DRS to work?
Hosts that are added to a DRS cluster must meet certain
requirements to use cluster features
successfully.
Shared Storage
Ensure that the managed hosts use shared storage. Shared storage
is typically on a SAN, but
can also be implemented using NAS shared storage.
Shared VMFS Volume
Configure all managed hosts to use shared VMFS volumes.
Place the disks of all virtual machines on VMFS volumes that are
accessible by source and
destination hosts.
Processor Compatibility
To avoid limiting the capabilities of DRS, you should maximize
the processor compatibility
of source and destination hosts in the cluster.
vMotion transfers the running architectural state of a virtual
machine between underlying
ESX/ESXi hosts. vMotion compatibility means that the processors
of the destination host
must be able to resume execution using the equivalent
instructions where the processors of
the source host were suspended. Processor clock speeds and cache
sizes might vary, but
processors must come from the same vendor class (Intel versus
AMD) and the same
processor family to be compatible for migration with
vMotion.
vCenter Server provides features that help ensure that virtual
machines migrated with
vMotion meet processor compatibility requirements. These
features include:
Enhanced vMotion Compatibility (EVC) You can use EVC to help
ensure vMotion compatibility for the hosts in a cluster. EVC
ensures that all hosts in a cluster present
the same CPU feature set to virtual machines, even if the actual
CPUs on the hosts
differ. This prevents migrations with vMotion from failing due
to incompatible CPUs.
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CPU compatibility masks vCenter Server compares the CPU features
available to a virtual machine with the CPU features of the
destination host to determine whether to
allow or disallow migrations with vMotion. By applying CPU
compatibility masks to
individual virtual machines, you can hide certain CPU features
from the virtual
machine and potentially prevent migrations with vMotion from
failing due to
incompatible CPUs.
vMotion Requirements
To enable the use of DRS migration recommendations, the hosts in
your cluster must be part
of a vMotion network. If the hosts are not in the vMotion
network, DRS can still make initial
placement recommendations.
To be configured for vMotion, each host in the cluster must meet
the following requirements:
The virtual machine configuration file for ESX/ESXi hosts must
reside on a VMware Virtual Machine File System (VMFS).
vMotion does not support raw disks or migration of applications
clustered using Microsoft Cluster Service (MSCS).
vMotion requires a private Gigabit Ethernet migration network
between all of the vMotion enabled managed hosts. When vMotion is
enabled on a managed host,
configure a unique network identity object for the managed host
and connect it to the
private migration network.
21. How vMotion works
There are 3 underlying action happening in vMotion.
First:-
The entire state of a virtual machine is encapsulated by a set
of files stored on shared storage
such as Fibre Channel or iSCSI Storage Area Network (SAN) or
Network Attached,Storage
(NAS).
VMware vStorage VMFS allows multiple ESX to access the same
virtual machine files
concurrently.
Second:-
The active memory and precise execution state of the virtual
machine is rapidly transferred
over a high speed network, allowing the virtual machine to
instantaneously switch from
running on the source ESX host to the destination ESX host.
VMotion keeps the transfer period imperceptible to users by
keeping track of on-going
memory transactions in a bitmap.
Once the entire memory and system state has been copied over to
the target ESX host,
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VMotion suspends the source virtual machine, copies the bitmap
to the target ESX host, and
resumes the virtual machine on the target ESX host.
This entire process takes less than two seconds on a Gigabit
Ethernet network.
Third:-
The networks being used by the virtual machine are also
virtualized by the underlying ESX
host, ensuring that even after the migration, the virtual
machine network identity and network
connections are preserved.
VMotion manages the virtual MAC address as part of the process.
Once the destination
machine is activated, VMotion pings the network router to ensure
that it is aware of the new
physical location of the virtual MAC address.
Since the migration of a virtual machine with VMotion preserves
the precise execution state,
the network identity, and the active network connections, the
result is zero downtime and no
disruption to users.
22. What are vSphere Standard Switches?
vSphere standard switches are abstracted network devices. A
standard switch can bridge
traffic internally between virtual machines in the same port
group and link to external
networks.
You can use standard switches to combine the bandwidth of
multiple network adapters and
balance communications traffic among them. You can also
configure a standard switch to
handle physical NIC failover.
A vSphere standard switch models a physical Ethernet switch. The
default number of logical
ports for a standard switch is 120. You can connect one network
adapter of a virtual machine
to each port. Each uplink adapter associated with a standard
switch uses one port. Each
logical port on the standard switch is a member of a single port
group. Each standard switch
can also have one or more port groups assigned to it.
When two or more virtual machines are connected to the same
standard switch, network
traffic between them is routed locally. If an uplink adapter is
attached to the standard switch,
each virtual machine can access the external network that the
adapter is connected to.
23. What is vSphere Distributed Switch?
The vSphere Distributed Switch (VDS) simplifies virtual machine
networking by enabling
you to set up virtual machine access switching for your entire
datacenter from a centralized
interface. VDS provides:
Simplify Virtual Machine Network Configuration
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Simplify provisioning, administration and monitoring of virtual
networking across multiple
hosts and clusters from a centralized interface.
Central control of virtual switch port configuration, portgroup
naming, filter settings, etc
Link Aggregation Control Protocol (LACP) - Negotiates and
automatically configures
link aggregation between vSphere hosts and access layer physical
switch
Network health check capabilities to verify vSphere to physical
network configuration
Enhanced network monitoring and troubleshooting capabilities
The vSphere Distributed Switch provides rich monitoring and
troubleshooting capabilities to
your networking staff
Support for RSPAN and ERSPAN protocols for remote network
analysis
IPFIX Netflow version 10
SNMPv3 support
Rollback and Recovery for Patching and Updating the Network
Configuration
Templates to enable backup and restore for virtual networking
configuration
Network based coredump (Netdump) to debug hosts without local
storage
Support advanced vSphere Networking Features
The vSphere Distributed Switch provides the building blocks for
many advanced networking
features in a vSphere environment.
Core building block for Network I/O Control (NIOC)
Maintains network runtime state for virtual machines as they
move across multiple hosts,
enabling inline monitoring and centralized firewall services
Supports third-party virtual switch extensions such as the Cisco
Nexus 1000V and IBM
5000v virtual switches
Support for SR-IOV (Single Root I/O Virtualization) to enable
low latency and high I/O
workloads
BPDU filter to prevent virtual machines from sending BPDUs to
the physical switch
24. What is the difference between standard switch (vSwitch) and
distributed switch (dvSwitch)?
Both types of switches provide the following:
Can forward L2 frames
Can segment traffic into VLANs
Can use and understand 802.1q VLAN encapsulation
Can have more than one uplink (NIC Teaming)
Can have traffic shaping for the outbound (TX) traffic
These features are available only with Distributed Switch:
Can shape inbound (RX) traffic
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Has a central unified management interface through vCenter
Supports Private VLANs (PVLANs)
Provides potential customization of Data and Control Planes
vSphere 5.0 provides these improvements to Distributed Switch
functionality:
Increased visibility of inter-virtual-machine traffic through
Netflow
Improved monitoring through port mirroring (dvMirror)
Support for LLDP (Link Layer Discovery Protocol), a
vendor-neutral protocol.
25. What is Port Group?
You can think of port groups as templates for creating virtual
ports with particular sets
of specifications. You can create a maximum of 512 port groups
on a single host.
Port groups are important particularly for VMotion. To
understand why, consider what
happens as virtual machines migrate to new hosts using
VMotion.
Port groups make it possible to specify that a given virtual
machine should have a particular
type of connectivity on every host on which it might run.
Port groups are user-named objects that contain configuration
information to provide
persistent and consistent network access for virtual Ethernet
adapters:
Virtual switch name
VLAN IDs and policies for tagging and filtering
Teaming policy
Layer 2security options
Traffic shaping parameters
In short, port group definitions capture all the settings for a
switch port. Then, when you
want to connect a virtual machine to a particular kind of port,
you simply specify the name of
a port group with an appropriate definition.
Port groups may specify different host-level parameters on
different hosts teaming
configurations, for example. But the key element is that the
result is a consistent view of the
network for a virtual machine connected to that port group,
whichever host is running it.
Note: Port groups do not necessarily correspond one-to-one to
VLAN groups. It is possible,
and even reasonable, to assign the same VLAN ID to multiple port
groups. This would be
useful if, for example, you wanted to give different groups of
virtual machines different
physical Ethernet adapters in a NIC team for active use and for
standby use, while all the
adapters are on the same VLAN.
26. How many ports we can have on a vSwitch?
ESX 2.x allowed only 32 virtual machines per vSwitch. ESX 3.x
raised the maximum
number of ports to 1016. In ESX 4.x, you can change the number
of ports to 24, 56, 120, 248,
504, 1016, 2040, or 4088.
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What might seem odd about these numbers is they are exactly
eight digits less than what you
might expect (32, 64, 128, 256, 512, 1032, 2048, and 4096). So
what happened to the other
eight ports? Well, those eight ports are there, but they are
used by the VMkernel for
background monitoring processes.
27. What are the three port groups present in ESX4 server
networking ?
1) Virtual Machine Port Group - Used for Virtual Machine
Network
2) Service Console Port Group - Used for Service Console
Communications
3) VMKernel Port Group - Used for VMotion, iSCSI, NFS
Communications
28. VMware vSphere 5 License types?
Standard: HA, FT, vMotion, Storage vMotion, vShield Endpoint,
Replication
Enterprise: Standard + DRS, DPM, Storage APIs, Virtual Serial
Port Concentrator
Enterprise Plus: Enterprise + Distributed Switch, Storage DRS
and Profile-Driven Storage, Host Profiles and Auto Deploy, Storage
I/O Control and Network I/O
Control
29. How to add license?
You can add any number of licenses to the vSphere 5.x inventory.
When assigning licenses
in 5.x products, you can create a relationship between an asset
and a license key. Each asset
can be licensed by one and only one license key or it can be
unlicensed as an Evaluation
Mode.
Note: To perform these steps, your vSphere Client needs to be
connected to the vCenter
Server.
Adding License Keys
To add licenses:
1. Log in to the vSphere Client. 2. Click Home. 3. Under the
Administration section, click the Licensing icon. 4. Click Manage
vSphere Licenses. 5. Enter the License Key in the Enter new vSphere
license keys field (one per line). 6. Include labels for new
license keys as necessary. 7. Click Add License Keys.
After clicking Add License Keys, you can review the license keys
you added, capacity
counts, expiration dates, and labels associated with the license
keys.
8. Click Next to assign the license keys.
Assigning License Keys
To assign licenses to the vCenter Server or the ESXi host:
-
1. Log in to the vSphere Client. 2. Click Home. 3. Under the
Administration section, click the Licensing icon. 4. Choose
Evaluation Mode and expand the list. Find the product you want to
license. 5. Right-click on the product and click Change License
Key. 6. Assign a key from list that was entered previously on
Manage License window. 7. Click OK. 8. Verify that the product is
licensed now.
30. VMware path selection policies?
These pathing policies can be used with VMware ESXi 5.x and
ESXi/ESX 4.x:
Most Recently Used (MRU): Selects the first working path,
discovered at system boot
time. If this path becomes unavailable, the ESXi/ESX host
switches to an alternative path
and continues to use the new path while it is available. This is
the default policy for
Logical Unit Numbers (LUNs) presented from an Active/Passive
array. ESXi/ESX does
not return to the previous path if, or when, it returns; it
remains on the working path until
it, for any reason, fails.
Note: The preferred flag, while sometimes visible, is not
applicable to the MRU pathing
policy and can be disregarded.
Fixed (Fixed): Uses the designated preferred path flag, if it
has been configured.
Otherwise, it uses the first working path discovered at system
boot time. If the ESXi/ESX
host cannot use the preferred path or it becomes unavailable,
the ESXi/ESX host selects
an alternative available path. The host automatically returns to
the previously-defined
preferred path as soon as it becomes available again. This is
the default policy for LUNs
presented from an Active/Active storage array.
Round Robin (RR): Uses an automatic path selection rotating
through all available
paths, enabling the distribution of load across the configured
paths.
o For Active/Passive storage arrays, only the paths to the
active controller will be
used in the Round Robin policy.
o For Active/Active storage arrays, all paths will be used in
the Round Robin
policy.
Note: This policy is not currently supported for Logical Units
that are part of a Microsoft
Cluster Service (MSCS) virtual machine.
Fixed path with Array Preference: The VMW_PSP_FIXED_AP policy
was introduced in
ESXi/ESX 4.1. It works for both Active/Active and Active/Passive
storage arrays that
support Asymmetric Logical Unit Access (ALUA). This policy
queries the storage array for
the preferred path based on the array's preference. If no
preferred path is specified by the
user, the storage array selects the preferred path based on
specific criteria.
-
Note: The VMW_PSP_FIXED_AP policy has been removed from ESXi
5.0. For ALUA
arrays in ESXi 5.0, the MRU Path Selection Policy (PSP) is
normally selected but some
storage arrays need to use Fixed.
31. What is swap size?
When you power on a VM, a memory swap file is created that can
be used in lieu of physical
host memory if an ESX host exhausts all of its physical memory
because it is overcommitted.
These files are created equal in size to the amount of memory
assigned to a VM, minus any
memory reservations (default is 0) that a VM may have set on it
(i.e., a 4 GB VM with a 1
GB reservation will have a 3 GB vswp file created).
32. What is ballooning?
Ideally, a VM from which memory has been reclaimed should
perform as if it had been
configured with less memory. ESX Server uses a ballooning
technique to achieve such
predictable performance by coaxing the guest OS into cooperating
with it when possible.
When the ESX hosts machine memory is scarce or when a VM hits a
Limit, The kernel needs to reclaim memory and prefers ballooning
over swapping. The balloon driver is
installed inside the guest OS as part of the VMware Tools
installation and is also known as
the vmmemctl driver.
When the ESX kernel wants to reclaim memory, it instructs the
balloon driver to inflate. The
balloon driver then requests memory from the guest OS. When
there is enough memory
available, the guest OS will return memory from its free list.
When there isnt enough memory, the guest OS will have to use its
own memory management techniques to decide
which particular pages to reclaim and if necessary page them out
to its swap- or page-file.
In the background, the ESX kernel frees up the machine memory
page that corresponds to the
physical machine memory page allocated to the balloon driver.
When there is enough
memory reclaimed, the balloon driver will deflate after some
time returning physical memory
pages to the guest OS again.
This process will also decrease the Host Memory Usage
parameter
Ballooning is only effective it the guest has available space in
its swap- or page-file, because
used memory pages need to be swapped out in order to allocated
the page to the balloon
driver. Ballooning can lead to high guest memory swapping.
33. What is thin provisioning?
When creating a virtual disk file, by default VMware ESXi/ESX
uses a thick type of virtual
disk. The thick disk pre-allocates all of the space specified
during the creation of the disk.
For example, if you create a 10 megabyte disk, all 10 megabytes
are pre-allocated for that
virtual disk.
In contrast, a thin virtual disk does not pre-allocate all of
the space. Blocks in the VMDK file
are not allocated and backed by physical storage until they are
written during the normal
-
course of operation. A read to an unallocated block returns
zeroes, but the block is not
backed with physical storage until it is written.
34. What is FT?
Fault Tolerance (FT) is a new feature in vSphere that takes
VMwares High Availability technology to the next level by providing
continuous protection for a virtual machine (VM)
in case of a host failure. It is based on the Record and Replay
technology that was introduced
with VMware Workstation that lets you record a VMs activity and
later play it back.
The feature works by creating a secondary VM on another ESX host
that shares the same
virtual disk file as the primary VM and then transferring the
CPU and virtual device inputs
from the primary VM (record) to the secondary VM (replay) via a
FT logging NIC so it is in
sync with the primary and ready to take over in case of a
failure. While both the primary and
secondary VMs receive the same inputs, only the primary VM
produces output such as disk
writes and network transmits. The secondary VMs output is
suppressed by the hypervisor and is not on the network until it
becomes a primary VM, so essentially both VMs function
as a single VM.
35. What is difference between HA and FT?
VMware Fault Tolerance is a high-availability feature that can
be used within a VMware
High Availability cluster. However, high availability is not
synonymous with fault tolerance;
there are meaningful differences between the two terms. Each
setup requires different
available resources and will affect virtual machines
differently.
The key difference between VMware's Fault Tolerance (FT) and
High Availability (HA)
products is interruption to virtual machine (VM) operation in
the event of an ESX/ESXi host
failure. Fault-tolerant systems instantly transition to a new
host, whereas high-availability
systems will see the VMs fail with the host before restarting on
another host.
VMware High Availability
VMware High Availability should be used to maintain uptime on
important but non-mission-
critical VMs. While HA cannot prevent VM failure, it will get
VMs back up and running
with very little disturbance to the virtual infrastructure.
Consider the value of HA for host
failures that occur in the early hours of the morning, when IT
is not immediately available to
resolve the problem.
In addition to tending to VMs during ESX/ESXi host failure,
VMware High Availability can
monitor and restart a VM, ensuring the machine is capable of
restarting on a new host with
enough resources.
VMware Fault Tolerance
VMware FT instantly moves VMs to a new host via vLockstep, which
keeps a secondary
VM in sync with the primary, ready to take over at any second,
like a Broadway understudy.
The VM's instructions and instruction sequence are the actor's
lines, which pass to the
-
understudy on a dedicated server backbone network. Heartbeats
ping between the star and
understudy on this backbone as well, for instantaneous detection
of a failure.
36. Difference between HA and vMotion?
VMotion and HA are not related and are not dependents of each
other. DRS have a
dependency on vMotion, but not HA. HA is used in the event that
a hosts fails you can have
your virtual machines restart on another host in the cluster.
vMotion allows you to move a
virtual machine from one host to another while it is running
without service
interruption. Ideally you will utilize vMotion, HA and DRS
within your cluster to achieve a
well-balanced VI environment.
37. What is Deference between ESX and ESXi?
VMware ESX Architecture. In the original ESX architecture, the
virtualization kernel
(referred to as the vmkernel) is augmented with a management
partition known as the
console operating system (also known as COS or service console).
The primary purpose of
the Console OS is to provide a management interface into the
host. Various VMware
management agents are deployed in the Console OS, along with
other infrastructure service
agents (e.g. name service, time service, logging, etc). In this
architecture, many customers
deploy other agents from 3rd parties to provide particular
functionality, such as hardware
monitoring and system management. Furthermore, individual admin
users log into the
Console OS to run configuration and diagnostic commands and
scripts.
VMware ESXi Architecture. In the ESXi architecture, the Console
OS has been
removed and all of the VMware agents run directly on the
vmkernel. Infrastructure
services are provided natively through modules included with the
vmkernel. Other authorized
3rd party modules , such as hardware drivers and hardware
monitoring components, can run
in vmkernel as well. Only modules that have been digitally
signed by VMware are allowed
on the system, creating a tightly locked-down architecture.
Preventing arbitrary code from
running on the ESXi host greatly improves the security of the
system.
Capability VMware ESX VMware ESXi
Service Console Service Console is a standard
Linux environment through
which a user has privileged
access to the VMware ESX
kernel. This Linux-based
privileged access allows you
to manage your
environment by installing agents
and drivers and executing scripts
VMware ESXi is designed
to make the server a
computing appliance.
Accordingly, VMware
ESXi behaves more like
firmware than traditional
software. To provide
hardware-like security and
reliability, VMware ESXi
does not support
a privileged access
-
and other Linux-environment
code.
environment like
the Service Console for
management of VMware
ESXi.
CLI-Based
Configuration
VMware ESX Service Console
has a host CLI through which
VMware ESX can be configured.
VMware ESX can also be
configured using vSphere CLI
(vCLI).
The vSphere CLI (vCLI) is
a remote scripting
environment that interacts
with VMware ESXi hosts
to enable host
configuration through
scripts or specific
commands. It replicates
nearly all the equivalent
COS commands for
configuring ESX.
Scriptable
Installation
VMware ESX supports scriptable
installations through utilities like
KickStart.
VMware ESXi Installable
does not support scriptable
installations in the manner
ESX does, at this time.
VMware ESXi does
provide support for post
installation configuration
script using vCLI-based
configuration scripts.
Boot from SAN VMware ESX supports boot from
SAN. Booting from SAN
requires one dedicated LUN per
server.
VMware ESXi may be
deployed as an embedded
hypervisor or installed on a
hard disk.
In most enterprise
settings, VMware ESXi is
deployed as an embedded
hypervisor directly on the
server. This operational
model does not require any
local storage and no SAN
booting is required because
the hypervisor image is
directly on the server.
The installable version of
VMware ESXi does not
support booting from SAN.
Serial Cable VMware ESX supports VMware ESXi does not
-
Connectivity interaction through direct-
attached serial cable to the
VMware ESX host.
support interaction through
direct-attached serial cable
to the VMware ESXi host
at this time.
SNMP VMware ESX supports SNMP. VMware ESXi supports
SNMP when licensed with
vSphere Essentials,
vSphere Essential Plus,
vSphere Standard, vSphere
Advanced, vSphere
Enterprise, or vSphere
Enterprise Plus.
The free version of
VMware ESXi does not
support SNMP.
Active Directory
Integration
VMware ESX supports Active
Directory integration through
third-party agents installed on the
Service Console.
VMware ESXi does not
support Active Directory
authentication of local
users at this time.
HW
Instrumentation
Service Console agents provide a
range of HW instrumentation on
VMware ESX.
VMware ESXi provides
HW instrumentation
through CIM Providers.
Standards-based CIM
Providers are distributed
with all versions of
VMware ESXi. VMware
partners include their own
proprietary CIM Providers
in customized versions of
VMware ESXi. These
customized versions are
available either from
VMwares web site or the
partners web site,
depending on the partner.
Remote console
applications like Dell
DRAC, HP iLO, IBM
RSA, and FSC iRMC
S2 are supported with
ESXi.
-
Software Patches
and Updates
VMware ESX software patches
and upgrades behave like
traditional Linux based patches
and upgrades. The installation of
a software patch or upgrade may
require multiple system boots as
the patch or upgrade may have
dependencies on previous
patches or upgrades.
VMware ESXi patches and
updates behave like
firmware patches and
updates. Any given patch
or update is all-inclusive of
previous patches and
updates. That is, installing
patch version n includes
all updates included in
patch versions n-1, n-2,
and so forth. Furthermore,
third party components
such as OEM CIM
providers can be updated
independently of the base
ESXi component, and vice
versa.
VI Web Access VMware ESX supports managing
your virtual machines through
VI Web Access. You can use the
VI Web Access to connect
directly to the ESX host or to the
VMware Infrastructure Client.
VMware ESXi does not
support web access at this
time.
Diagnostics and
Troubleshooting
VMware ESX Service Console
can be used to issue commands
that can help diagnose and repair
support issues with the server.
VMware ESXi has several
ways to enable support of
the product:
Remote command sets
such as the vCLI include
diagnostic commands such
as vmkfstools, resxtop, and
vmware-cmd.
The console interface of
VMware ESXi (known as
the DCUI or Direct
Console User Interface)
has functionality to help
repair the system,
including restarting of all
management agents.
-
Tech Support Mode, which
allows low-level access to
the system so that
advanced diagnostic
commands can be issues.
38. Difference between vSphere 4.1 and vSphere 5?
Features vSphere 4.1 vSphere 5.0
Hypervisor ESX & ESXi Only ESXi
VMA Yes VMA 4.1 Yes VMA 5
HA Agent
AAM
Automatic Availability
Manager
FDM
Fault Domain Manager
HA Host Approach Primary & Secondary Master & Slave
HA Failure Detection Management N/W
Management N/W and Storage
communication
HA Log File /etc/opt/vmware/AAM /etc/opt/vmware/FDM
DNS Dependent on DNS Yes NO
Host UEFI boot support NO
boot systems from hard drives,
CD/DVD drives, or USB media
Storage DRS Not Available Yes
VM Affinity & Anti-Affinity Available Available
VMDK Affinity & Anti-
Affinity Not Available Available
Profile driven storage Not Available Available
VMFS 5 VMFS-3 VMFS-5
VSphere Storage Appliance Not Available Available
-
Iscsi Port Binding GUI
Can be only done via Cli
using ESXCLI
Configure dependent
hardware iSCSI and software
iSCSI adapters along with the
network configurations and
port binding in a single dialog
box using the vSphere Client.
Storage I/O control for NFS Fiber Channel Fiber Channel &
NFS
Storage Vmotion Snapshot
support
VM with Snapshot cannot be migrated
using Storage vMotion
VM with Snapshot can be
migrated using Storage vMotion
Swap to SSD NO Yes
Network I/O control Yes Yes with enhancement
ESXi firewall Not Available Yes
vCenter Linux Support Not Available vCenter Virtual
Appliance
vSphere Full Client Yes Yes
vSphere Web Client Yes yes with lot of improvements
VM Hardware Version 8 7 8
Virtual CPU per VM 8 vCpu 32 vCpu
Virtual Machine RAM 255 GB 1 TB of vRAM
VM Swapfile size 255 GB 1 TB
Support for Client
connected USB Not Available Yes
Non Hardware Accelerated
3D grpahics support Not Available Yes
UEFI Virtual BIOS Not Available Yes
VMware Tools Version 4.1 5
Mutlicore vCpu Not Available Yes configure at VM setting
MAC OS Guest Support Not Available Apple Mac OS X Server
10.6
Smart card reader support
for VM Not Available Yes
-
Auto Deploy Not Available Yes
Image Builder Not Available Yes
VM's per host 320 512
Max Logical Cpu per Host 160 160
RAM per Host 1 TB 2 TB
MAX RAM for Service
Console 800 MB Not Applicable (NO SC)
LUNS per Server 256 256
Metro Vmotion
Round-trip latencies of up to
5 milliseconds.
Round-trip latencies of up to
10 milliseconds. This provides
better performance over
long latency networks
Storage Vmotion
Moving VM Files using moving to using
dirty block tracking
Moving VM Files using I/O
mirroring with better
enhancements
Virtual Distributed Switch Yes
Yes with more enhancements
like deeper view into virtual
machine traffic through Netflow
and enhances monitoring and
troubleshooting capabilities
through SPAN and LLDP
USB 3.0 Support NO Yes
Host Per vCenter 1000 1000
Powered on virtual
machines
per vCenter Server 10000 10000
Vmkernel 64-bit 64-bit
Service Console 64-bit Not Applicable (NO SC)
-
Licensing
vSphere Essentials
vSphere Essentials Plus
vSphere Standard
vSphere Advanced
vSphere Enterprise
vSphere Enterprise Plus
vSphere Essentials
vSphere Essentials Plus
vSphere Standard
vSphere Enterprise
vSphere Enterprise Plus
39. Describe vSphere 5 Licensing?
vSphere 5 has changed entitlements around CPU cores and memory
use. vSphere 5 has
also introduced a small change to the entitlement process around
what is known as virtual
memory or vRAM.
40. What is vRAM pool?
vRAM or virtual RAM is the total memory configured to a virtual
machine;
Available pooled vRAM is equal to the sum total of vRAM
entitlements for all VMware
-
vSphere licenses of a single edition, managed by a single
instance of VMware vCenter
Server or by multiple instances of VMware vCenter Server in
Linked Mode.
41. What difference between VMFS 3 and VMFS 5?
VMFS3
Volume size 64TB
Raw device mapping size (virtual compatibility) 2TB minus 512
bytes
Raw Device Mapping size (physical compatibility) 2TB minus 512
bytes
Block size 8MB
File size (1MB block size) 256GB
File size (2MB block size) 512GB
File size (4MB block size) 1TB
File size (8MB block size) 2TB minus 512 bytes
Files per volume Approximately 30,720
VMFS5
Volume size 64TB
Raw Device Mapping size (virtual compatibility) 2TB minus 512
bytes
Raw Device Mapping size (physical compatibility) 64TB
Block size 1MB
File size 2TB minus 512 bytes
Files per volume Approximately 130,690
42. How to enable Tech Support mode in ESX 3.5?
ESXi 3.5 does ship with the ability to run SSH, but this is
disabled by default (and is not
supported). If you just need to access the console of ESXi, then
you only need to perform
steps 1 - 3.
1. At the console of the ESXi host, press ALT-F1 to access the
console window. 2. Enter unsupported in the console and then press
Enter. You will not see the
text you type in.
3. If you typed in unsupported correctly, you will see the Tech
Support Mode warning and a password prompt. Enter the password for
the root login.
You should then see the prompt of ~ #.
43. How to enable Tech Support mode in ESXi 4.1?
Tech Support Mode (TSM) provides a command-line interface that
can be used by the
administrator to troubleshoot and correct abnormal conditions on
VMware ESXi hosts.
TSM can be accessed in two ways:
-
Logging in directly on the console of the ESXi server.
Logging in remotely via SSH.
44. How to enable Tech Support mode using CLI?
To enable/disable and start/stop the local ESXi Shell or local
TSM from the local
command line on the ESXi host:
To start the ESXi Shell or local TSM, run the command:
ESXi 5.x vim-cmd hostsvc/start_esx_shell ESXi 4.1 vim-cmd
hostsvc/start_local_tsm
To disable the ESXi Shell or local TSM, run the command:
ESXi 5.x vim-cmd hostsvc/disable_esx_shell ESXi 4.1 vim-cmd
hostsvc/disable_local_tsm
To stop the ESXi Shell or local TSM, run the command:
ESXi 5.x vim-cmd hostsvc/stop_esx_shell ESXi 4.1 vim-cmd
hostsvc/stop_local_tsm
45. What are the files that make a Virtual Machine?
.vmx - Virtual Machine Configuration File
.nvram - Virtual Machine BIOS
.vmdk - Virtual Machine Disk file
.vswp - Virtual Machine Swap File
.vmsd - Virtual Machine Snapshot Database
.vmsn - Virtual Machine Snapshot file
.vmss - Virtual Machine Suspended State file
.vmware.log - Current Log File
.vmware-#.log - Old Log file
vswp file is only present when the VM is powered on and the
.vmss file is only
present when a VM is suspended.
46. What is the .nvram file?
This small file contains the Phoenix BIOS that is used as part
of the boot process of the
virtual machine. It is similar to a physical server that has a
BIOS chip that lets you set
hardware configuration options. A VM also has a virtual BIOS
that is contained in the
NVRAM file. The BIOS can be accessed when a VM first starts up
by pressing the F2
key. Whatever changes are made to the hardware configuration of
the VM are then saved
in the NVRAM file. This file is in binary format and if deleted
it will be automatically re-
created when a VM is powered on.
-
47. What is the .vmx file?
This file contains all of the configuration information and
hardware settings of the virtual
machine. Whenever you edit the settings of a virtual machine,
all of that information is
stored in text format in this file. This file can contain a wide
variety of information about
the VM, including its specific hardware configuration (i.e., RAM
size, network interface
card info, hard drive info and serial/parallel port info),
advanced power and resource
settings, VMware tools options, and power management options.
While you can edit this
file directly to make changes to a VM's configuration it is not
recommended that you do
so unless you know what you are doing. If you do make changes
directly to this file, it's a
very good idea to make a backup copy of this file first.
48. What are VMDK files?
All virtual disks are made up of two files, a large data file
equal to the size of the virtual
disk and a small text disk descriptor file, which describes the
size and geometry of the
virtual disk file. The descriptor file also contains a pointer
to the large data file as well as
information on the virtual disks drive sectors, heads, cylinders
and disk adapter type. In
most cases these files will have the same name as the data file
that it is associated with
(i.e., myvm_1.vmdk and myvm_1-flat.vmdk). You can match the
descriptor file to the
data file by checking the Extent Description field in this file
to see which flat, -rdm or delta file is linked to it. An example
disk descriptor file is shown below:
The three different types of virtual disk data files that can be
used with virtual machines
are covered below:
The flat.vmdk file
This is the default large virtual disk data file that is created
when you add a
virtual hard drive to your VM that is not an RDM. When using
thick disks, this
file will be approximately the same size as what you specify
when you create your
virtual hard drive. One of these files is created for each
virtual hard drive that a VM
has configured, as shown in the examples below.
-
The delta.vmdk file
These virtual disk data files are only used when snapshots are
created of a virtual
machine. When a snapshot is created, all writes to the original
flat.vmdk are halted and it becomes read-only; changes to the
virtual disk are then written to these delta files instead. The
initial size of these files is 16 MB and they are grown as needed
in 16
MB increments as changes are made to the VM's virtual hard disk.
Because these files are
a bitmap of the changes made to a virtual disk, a single
delta.vmdk file cannot exceed the size of the original flat.vmdk
file. A delta file will be created for each snapshot that you
create for a VM and their file names will be incremented
numerically (i.e., myvm-
000001-delta.vmdk, myvm-000002-delta.vmdk). These files are
automatically deleted
when the snapshot is deleted after they are merged back into the
original flat.vmdk file.
-
The -rdm.vmdk file
This is the mapping file for the RDM that manages mapping data
for the RDM
device. The mapping file is presented to the ESX host as an
ordinary disk file,
available for the usual file system operations. However, to the
virtual machine the
storage virtualization layer presents the mapped device as a
virtual SCSI device. The
metadata in the mapping file includes the location of the mapped
device (name
resolution) and the locking state of the mapped device. If you
do a directory listing
you will see that these files will appear to take up the same
amount of disk space on
the VMFS volume as the actual size of the LUN that it is mapped
to, but in reality
they just appear that way and their size is very small. One of
these files is created for
each RDM that is created on a VM.
-
49. What is the .vswp file?
When you power on a VM, a memory swap file is created that can
be used in lieu of
physical host memory if an ESX host exhausts all of its physical
memory because it
is overcommitted. These files are created equal in size to the
amount of memory
assigned to a VM, minus any memory reservations (default is 0)
that a VM may have set
on it (i.e., a 4 GB VM with a 1 GB reservation will have a 3 GB
vswp file created). These
files are always created for virtual machines but only used if a
host exhausts all of its
physical memory. As virtual machine memory that is read/written
to disk is not as fast as
physical host RAM, your VMs will have degraded performance if
they do start using this
file. These files can take up quite a large amount of disk space
on your VMFS volumes,
so ensure that you have adequate space available for them, as a
VM will not power on if
there is not enough room to create this file. These files are
deleted when a VM is powered
off or suspended.
50. What is the .vmss file?
This file is used when virtual machines are suspended and is
used to preserve the
memory contents of the VM so it can start up again where it left
off. This file will be
approximately the same size as the amount of RAM that is
assigned to a VM (even empty
memory contents are written). When a VM is brought out of a
suspend state, the contents
of this file are written back into the physical memory of a host
server, however the file is
not automatically deleted until a VM is powered off (an OS
reboot won't work). If a
previous suspend file exists when a VM is suspended again, this
file is re-used instead of
deleted and re-created. If this file is deleted while the VM is
suspended, then the VM will
start normally and not from a suspended state.
51. What is the .vmsd file?
This file is used with snapshots to store metadata and other
information about each
snapshot that is active on a VM. This text file is initially 0
bytes in size until a snapshot
is created and is updated with information every time snapshots
are created or deleted.
Only one of these files exists regardless of the number of
snapshots running, as they all
update this single file. The snapshot information in this file
consists of the name of the
VMDK and vmsn file used by each snapshot, the display name and
description, and the
UID of the snapshot. Once your snapshots are all deleted this
file retains old snapshot
information but increments the snapshot UID to be used with new
snapshots. It also
renames the first snapshot to "Consolidate Helper," presumably
to be used with
consolidated backups.
52. What is the .vmsn file?
This file is used with snapshots to store the state of a virtual
machine when a
snapshot is taken. A separate .vmsn file is created for every
snapshot that is created on a
VM and is automatically deleted when the snapshot is deleted.
The size of this file will
vary based on whether or not you choose to include the VM's
memory state with your
snapshot. If you do choose to store the memory state, this file
will be slightly larger than
the amount of RAM that has been assigned to the VM, as the
entire memory contents,
-
including empty memory, is copied to this file. If you do not
choose to store the
memory state of the snapshot then this file will be fairly small
(under 32 KB). This
file is similar in nature to the .vmss that is used when VMs are
suspended.
53. What is the .log file?
These are the files that are created to log information about
the virtual machine and
are oftentimes used for troubleshooting purposes. There will be
a number of these
files present in a VM's directory. The current log file is
always named vmware.log and up
to six older log files will also be retained with a number at
the end of their names (i.e.,
vmware-2.log). A new log file is created either when a VM is
powered off and back on or
if the log file reaches the maximum defined size limit. The
amount of log files that are
retained and the maximum size limits are both defined as VM
advanced configuration
parameters (log.rotateSize and log.keepOld).
54. What is the .vmxf file?
This file is a supplemental configuration file that is not used
with ESX but is
retained for compatibility purposes with Workstation. It is in
text format and is used
by Workstation for VM teaming where multiple VMs can be assigned
to a team so they
can be powered on or off, or suspended and resumed as a single
object.
55. How to know registered VM on Host using CLI?
List All VMs on the Host
# vim-cmd vmsvc/getallvms
Get Information for a Specific VM
# vim-cmd vmsvc/get.guest 30
Get Configuration for a Specific VM
# vim-cmd vmsvc/get.config 30
Get Summary for a Specific VM
# vim-cmd vmsvc/get.summary 30
Get Current Power State of a Specific VM
# vim-cmd vmsvc/power.getstate 30
Power On a Specific VM
# vim-cmd vmsvc/power.on 30
Power Off a Specific VM (Hard)
# vim-cmd vmsvc/power.off 30
Shutdown a Specific VM
# vim-cmd vmsvc/power.shutdown 30
Reboot a Specific VM
-
# vim-cmd vmsvc/power.reset 30
List a Specific VMs Snapshots
# vim-cmd vmsvc/get.snapshot 30
Unregister a VM from a ESX Host
# vim-cmd vmsvc/unregister 30
Register a VM on a ESX Host
# vim-cmd solo/registervm path/to/.vmx
56. How many Hosts can we have in a Cluster in vCenter 5?
HA does not limit the number of hosts in a cluster. Using more
hosts in a cluster
results in less overhead. (N+1 for 8 hosts vs N+1 for 32
hosts)
Big clusters are good for DRS. More hosts equals more scheduling
opportunities.
Max number of hosts accessing a file = 8 .This is a constraint
in an environment using
linked clones like VMware View, vCloud Director.
Max values in general (256 LUNs, 1024 Paths, 512 VMs per host,
3000 VMs per cluster)
57. What are Resource Pool, Allocation and Priority?
A VMware ESX Resource pool is a pool of CPU and memory
resources. Inside the pool,
resources are allocated based on the CPU and memory shares that
are defined. This pool
can have associated access control and permissions.
58. What is PVLAN?
A private VLAN is a technique in computer networking where a
VLAN contains
switch ports that are restricted, such that they can only
communicate with a given
"uplink". The restricted ports are called "private ports". Each
private VLAN typically
contains many private ports, and a single uplink. The uplink
will typically be a port (or
link aggregation group) connected to a router, firewall, server,
provider network, or
similar central resource.
The switch forwards all frames received on a private port out
the uplink port, regardless
of VLAN ID or destination MAC address. Frames received on an
uplink port are
forwarded in the normal way (i.e., to the port hosting the
destination MAC address, or to
all VLAN ports for unknown destinations or broadcast frames).
"Peer-to-peer" traffic is
blocked. Note that while private VLANs provide isolation at the
data link layer,
communication at higher layers may still be possible.
59. Which file is created during vMotion?
A second vswp file gets created during a VMotion.
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60. Which one ver. of MS SQL required for Windows vCenter?
Microsoft SQL Server 2008 Standard (R2) - 64-bit
Microsoft SQL Server 2008 Standard (R2) - 32-bit
Microsoft SQL Server 2008 Express (R2) - 64-bit
Microsoft SQL Server 2008 Express (R2 SP1) - 64-bit
Microsoft SQL Server 2008 Enterprise (R2) - 64-bit
Microsoft SQL Server 2008 Enterprise (R2) - 32-bit
Microsoft SQL Server 2008 Datacenter Edition (SP2) -64-bit
Microsoft SQL Server 2008 Standard Edition (SP2) -32-bit
61. What you understand by Appliances?
A virtual appliance is a virtual machine image designed to run
on a virtualization
platform (e.g., VirtualBox, Xen, VMware Workstation, Parallels
Workstation).
Virtual appliances are a subset of the broader class of software
appliances. Installation of
a software appliance on a virtual machine creates a virtual
appliance. Like software
appliances, virtual appliances are intended to eliminate the
installation, configuration and
maintenance costs associated with running complex stacks of
software.
62. What are VMware vCloud Director 1.5 Config Maximums?
Type: Virtual machines per vCloud Director
Limit: 20000
Description: The maximum number of virtual machines that may be
resident in a vCloud
instance.
Type: Powered on VMs per vCloud Director
Limit: 10000
Description: Number of concurrently powered on virtual machines
permitted per vCloud
instance.
Type: Virtual machines per vApp
Limit: 128
Description: The maximum number of virtual machines that can
reside in a single vApp.
Type: Hosts per vCloud Director
Limit: 2000
Description: Number of hosts that can be managed by a single
vCloud instance.
Type: vCenter Servers per vCloud Director
Limit: 25
Description: Number of vCenter servers that can be managed by a
single vCloud
instance.
Type: Users per vCloud Director
Limit: 10000
-
Description: The maximum number of users that can be managed by
a single vCloud
instance.
Type: Organizations per vCloud Director
Limit: 10000
Description: The maximum number of organizations that can be
created in a single
vCloud instance.
Type: vApps per organization
Limit: 500
Description: The maximum number of vApps that can be deployed in
a single
organization.
Type: Virtual datacenters per vCloud Director
Limit: 5000
Description: The maximum number of virtual datacenters that can
be created in a single
vCloud instance.
Type: Datastores per vCloud Director
Limit: 1024
Description: Number of datastores that can be managed by a
single vCloud instance.
Type: Networks per vCloud Director
Limit: 7500
Description: The maximum number of logical networks that can be
deployed in a single
vCloud instance.
Type: Catalogs per vCloud Director
Limit: 1000
Description: The maximum number of catalogs that can be created
in a single vCloud
instance.
Type: Media Items per vCloud Director
Limit: 1000
Description: The maximum number of media items which can be
created in a single
vCloud instance.
63. Explain the entire process of P2V conversion?
Below are the steps you should take to prepare your server for
conversion.
1) Install the Converter application on the server being
migrated. If you are using the Enterprise version you can do this
remotely, but my preference is to install Converter
directly on to the server a potential complication caused by
introducing another PC in
the conversion process. If you have many machines to convert
this is not always
practical. The Converter application consists of two parts, the
Agent component
(Windows service) and the Manager component (front end GUI). If
you are running
-
this on the server directly you need both components. Otherwise
if you are running it
remotely only the Agent component is needed.
2) Once you install the application on the server a reboot will
be required if the server OS is Windows NT 4.0 or 2000. This is
because a special driver is installed for the
cloning process on those OS's, Windows XP and 2003 utilize the
Volume Shadow
Copy service instead. Also, it's best to use a local
administrator account when logging
into the server to install the application.
3) The following Windows services must be running for Converter
to work properly: Workstation, Server, TCP/IP Netbios Helper and
Volume Shadow Copy (Windows XP/2003, can be set to manual, just not
disabled). Also, disable Windows
Simple File Sharing if your source server is running Windows
XP.
4) Make sure the VMware Converter Windows service is
running.
5) Ensure you have at least 200 MB free on your source server's
C drive. Mirrored or striped volumes across multiple disks should
be broken; hardware RAID is OK since
it is transparent to the operating system. Converter sometimes
has issues converting
dynamic disks, if you experience problems with them, then cold
clone instead.
6) Disable any antivirus software running on the source
server.
7) Shutdown any applications that are not needed on the
server.
8) Run chkdsk and defragment your source server's hard
disks.
9) Clean-up any temporary and unnecessary files on the source
server. The less data that needs to be copied the better. This only
applies when utilizing file level cloning (more
on that later).
10) Keep users off the server while cloning. Disable remote
desktop and any shares if possible.
11) Ensure required TCP/UDP ports are opened between the source
server and VirtualCenter (VC) and VMware ESX. Even if you select
VirtualCenter as your
destination, the ports still need to be opened to the ESX server
you choose. The
source server first contacts VC to create the VM and then ESX to
transfer the data to.
Required ports are 443 and 902 (source to ESX/VC) and 445 and
139 (converter to
source and source to Workstation/Server). These ports need to be
opened on both OS
firewalls and any network firewalls sitting between your source
and destination
servers.
12) Ensure your network adapter speed/duplex matches your
physical switch setting. This can have a dramatic effect on your
conversion speed. When cold cloning it's best to
set your physical switch port to Auto/Auto since this is what
the Windows PE ISO
will default to.
13) If importing a VM or physical image the Windows version of
the server running Converter must be equal to or greater than the
source. So, if your source is Windows
2003, the server running Converter cannot be Windows 2000.
14) For cold cloning, the minimum memory requirement is 264 MB
(will not work with less than this amount), the recommended memory
is 364 MB. Converter also utilizes
a RAM disk if you have at least 296 MB of memory available.
-
Making the conversion
With these steps complete, we're ready to get started. Start the
Converter Manager
application and click the Import Machine button to start the
Converter Wizard. Select
your Source server, in this example we will choose Physical
Computer. Select This Local
Machine if running Converter on the source server, otherwise
enter the hostname/IP and
login information of the server to be converted. At the Source
Data screen you have the
option to select your disk volumes and re-size then larger or
smaller if needed. Make sure
you do not select any small utility partitions created by your
hardware installation. What
you decide here will determine which disk cloning method is used
to copy your source
data. If you do not change your drive sizes or increase them,
then a block-level clone will
be performed. If you decrease the size of your drives by any
amount then a file-level
clone will be performed instead.
When a block-level clone is performed, data is transferred from
the source server disk to
the destination server disk block-by-block. This method is
faster but results in more data
being copied (even empty disk blocks are copied). When a
file-level clone is performed,
data is instead transferred file-by-file, which is slower but
results in less data being
copied. So if you only have 5 GB of data on a 40 GB drive, then
only the 5 GB is copied.
It's a trade-off between the two methods between faster transfer
speed versus reduced
data size which often results in about the same time to copy the
data. One potential caveat
with the file-level copy is if you have a server with a huge
amount of small files, it can
take days to copy the data, and will sometimes fail. I
experienced a server with 200,000+
2 K files in one directory which brought the conversion to a
crawl. Once I removed these
files it completed in a few hours.
Next choose your destination server which is typically
VirtualCenter (VC)/ESX. If you
have a VC server managing a destination ESX server, it is best
to choose the VC server
first. Continue entering a VM name, host and datastore; at the
Networks screen you can
select one or more NIC's and networks to connect to.
My preference is to first connect the VM to an Internal Only
vSwitch so it is isolated
from the source server and I can power it on while the source
server is still up. Once I
verify that the newly created VM is functioning properly and I
go through the post-clone
procedures, I shut down the source server and move the VM to the
same network that the
source server was on.
Finally select whether or not to install VMware Tools, enter any
OS customization if
necessary, select whether or not to power on the VM right after
the conversion completes
and click the Finish button to start the conversion process.
Once the conversion starts you
can monitor the progress in the task progress window.
64. Difference between hot clone and cold clone?
Hot cloning: Convert physical machines while they are still
running
Cold cloning: Convert physical machines using a BootCD (download
from VMware site)
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65. What is VMware VMotion & Storage VMotion (SVMotion)?
With VMotion, VM guests are able to move from one ESX Server to
another with no
downtime for the users. What is required is a shared SAN storage
system between the
ESX Servers and a VMotion license.
Storage VMotion (or SVMotion) is similar to VMotion in the sense
that it moves VM
guests without any downtime. However, what SVMotion also offers
is the capability to
move the storage for that guest at the same time that it moves
the guest. Thus, you could
move a VM guest from one ESX servers local storage to another
ESX servers local storage with no downtime for the end users of
that VM guest.
66. What are the three port groups present in ESX4 server
networking
1. Virtual Machine Port Group - Used for Virtual Machine
Network
2. Service Console Port Group - Used for Service Console
Communications
3. VMKernel Port Group - Used for VMotion, iSCSI, NFS
Communications
67. What is the use of a Port Group?
The port group segregates the type of communication.
68. What is the type of communications which requires an IP
address for sure?
Service Console and VMKernel (VMotion and iSCSI), these
communications does not
happen without an ip address (Whether it is a single or
dedicated)
69. In the ESX Server licensing features VMotion License is
showing as Not used, why?
Even though the license box is selected, it shows as "License
Not Used" until, you enable
the VMotion option for specific vSwitch
70. How the Virtual Machine Port group communication works?
All the vm's which are configured in VM Port Group are able to
connect to the physical
machines on the network. So this port group enables
communication between vSwitch
and Physical Switch to connect vm's to Physical Machine's
71. What is a VLAN?
A VLAN is a logical configuration on the switch port to segment
the IP Traffic. For this
to happen, the port must be trunked with the correct VLAN
ID.
72. Does the vSwitches support VLAN Tagging? Why?
Yes, The vSwitches support VLAN Tagging, otherwise if the
virtual machines in an esx
host are connected to different VLANS, we need to install a
separate physical nic
-
(vSwitch) for every VLAN. That is the reason vmware included the
VLAN tagging for
vSwitches. So every vSwitch supports upto 1016 ports, and BTW
they can support 1016
VLANS if needed, but an ESX server doesnt support that many VMs.
:)
73. What is Promiscuous Mode on vSwitch ? What happens if it
sets to accept?
Accept: Placing a guest adapter in promiscuous mode causes it to
detect all frames passed
on the vSphere standard switch that are allowed under the VLAN
policy for the port group
that the adapter is connected to.
Reject: Placing a guest adapter in promiscuous mode has no
effect on which frames are
received by the adapter.
74. What is MAC address Changes? What happens if it is set to
accept?
Accept: Changing the MAC address from the Guest OS has the
intended effect: frames to the
new MAC address are received.
Reject: If you set the MAC Address Changes to Reject and the
guest operating system
changes the MAC address of the adapter to anything other than
what is in the .vmx
configuration file, all inbound frames are dropped.
If the Guest OS changes the MAC address back to match the MAC
address in the .vmx
configuration file, inbound frames are passed again.
75. What is Forged Transmits? What happens if it is set to
accept?
Accept No filtering is performed and all outbound frames are
passed.
Reject Any outbound frame with a source MAC address that is
different from the one currently set on the adapter are
dropped.
76. What are the core services of VC?
VM provisioning, Task Scheduling and Event Logging
77. Can we do vMotion between two datacenters? If possible how
it will be?
Yes we can do vMotion between two datacenters, but the mandatory
requirement is the
VM should be powered off.
78. What is VC agent? And what service it is corresponded to?
What are the minimum requirements for VC agent installation?
VC agent is an agent installed on ESX server which enables
communication between VC
and ESX server. The daemon associated with it is called
vmware-hostd , and the service
which corresponds to it is called as mgmt-vmware, in the event
of VC agent failure just
restart the service by typing the following command at the
service console
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79. "service mgmt-vmware restart " 80. How can you edit VI
Client Settings and VC Server Settings?
Click Edit Menu on VC and Select Client Settings to change VI
settings
Click Administration Menu on VC and Select VC Management Server
Configuration to
Change VC Settings
81. What are the files that make a Virtual Machine?
.vmx - Virtual Machine Configuration File
.nvram - Virtual Machine BIOS
.vmdk - Virtual Machine Disk file
.vswp - Virtual Machine Swap File
.vmsd - Virtual Machine Sna