VMware vSphere PowerCLI Release Notes

About VMware vSphere PowerCLI

vSphere PowerCLI is a command-line and scripting tool built on Windows PowerShell, and provides more than 200 cmdlets for managing and automating vSphere.


To use vSphere PowerCLI, you need to have installed the followming software:

  • .NET 2.0, 3.0, or 3.5 with Service Pack 1
  • Windows PowerShell 1.0/2.0

If .NET is installed without Service Pack 1, some operations might take long to complete.

Supported Platforms

vSphere PowerCLI 5.0 works on the 32-bit and 64-bit versions of the following operating systems:

  • Windows 7
  • Windows 2008 Server
  • Windows Vista
  • Windows XP Service Pack 2
  • Windows Server 2003 Service Pack 2

The following PowerCLI features are supported only on the 32-bit versions of the supported operating systems.

  • New-OSCustomizationSpec and Set-OSCustomizationSpec
  • New-VM and Set-VM (only when used for applying customization specifications)
  • Invoke-VMScript
  • Copy-VMGuestFile
  • New-VMGuestRoute, Get-VMGuestRoute, and Remove-VMGuestRoute
  • New-VMGuestNetworkInterface and Set-VMGuestNetworkInterface
  • Set-HardDisk ( only when used for resizing guest disk partitions)

vSphere PowerCLI 5.0 supports the following VMware environments:

  • VMware ESXi 5.0
  • vCenter Server 5.0
  • VMware ESX 4.1 / vCenter Server 4.1
  • VMware ESXi 4.1
  • VMware ESX 4.0 Update 2 / vCenter Server 4.0 Update 2
  • VMware ESX 4.0 Update 1 / vCenter Server 4.0 Update1
  • VMware ESX 4.0i Update 1
  • VMware VirtualCenter 2.5 Update 6
  • VMware ESX 3.5 Update 5
  • VMware ESXi 3.5 Update 5
  • VMware ESX 3.0.3 Update1

What’s New in This Release?

New Features

This release of vSphere PowerCLI introduces the following new capabilities:

  • Cloning templates with New-Template.
  • Copying files and folders from and to the guest operating system through the Copy-VMGuestFile cmdlet.
  • Joining domains through the Get-VMHostAuthentication and Set-VMHostAuthentication cmdlets.
  • Joining ESX hosts (version 4.1 and later) into an active directory through the Get-VMHostAuthentication and Set-VMHostAuthentication cmdlets.
  • Retrieving vCenter Server users and groups through the Get-VIAccount cmdlet.
  • Support for vCenter Servers in linked mode through the Connect-VIServer cmdlet.
  • Retrieving object properties through the Get-VIProperty cmdlet.
  • Moving virtual appliances through the Move-VApp cmdlets.
  • Importing compressed and chunked files through the Import-VApp cmdlet.
  • Importing and exporting virtual appliances in OVA format.
  • Support for the SSPI passthrough feature of VIX.
  • Support for storage DRS: creating virtual machines and hard disks on datastore clusters and defining anti-affinity rules.(experimental)

Additional Snapins

vSphere PowerCLI 5.0 introduces three additional snapins of cmdlets that cover specific vSphere functionalities:

  • VMware.VimAutomation.License : The Licensing snapin contains the Get-LicenseDataManager cmdlet for managing VMware License components..
  • VMware.ImageBuilder : The Image Builder snapin contains cmdlets for managing depots, image profiles, and VIBs.
  • VMware.DeployAutomation : The Auto Deploy snapin contains cmdlets that provide an interface to VMware Auto Deploy for provisioning physical hosts with ESXi software.

Discontinued Support

Support for PowerShell 1.0 will be removed in the next PowerCLI release.

For more information on changes made in vSphere PowerCLI 5.0, see the vSphere PowerCLI Change Log.

Obtaining the Software

You can obtain the vSphere PowerCLI 5.0 from here.

Known Issues

vSphere PowerCLI 5.0 is known to have the following issues:



      runs in asynchronous mode even when called without the





    throws an error when uploading an item to the root folder of a Datastore Provider drive.


      On vCenter Server 5.0,


    cannot change the storage format of the destination hard disk.



    might not return the actual datastore free space after a virtual machine is powered on. A refresh should be made first.


      On ESX 3.5,


      throws an error and does not create a datastore, although the specified


      disk partition is formatted with VMFS and you can run


    to create a datastore from the formatted partition.


      The value of the


      property of the object returned by


    is different depending on the way the hard disk is obtained by the cmdlet.


  • Get-NetworkAdapter does not throw an error message if you try to retrieve a nonexisting adapter.
  • Get-NetworkAdapter returns only one object, when you try to retrieve existing network adapters by name from two virtual machines or snapshots.


      When you use


      to retrieve Powerpath devices, the value of their


      property is shown as






      parameter of


      does not accept




  • Get-UsbDevice does not work on ESX Server 3.5 Update 4 and ESX Server 3.5i platforms.
  • Get-UsbDevice cannot obtain USB devices from snapshots.


  • If a nonexisting user is specified, Get-VIEvent returns the events for all existing users.
  • Objects returned by Get-VIEvent contain ManagedObjectReference types that are not compatible with the Get-View cmdlet.


  • During the process of creating a template from a virtual machine, Get-VM returns both the virtual machine and template objects.
  • If you try to retrieve virtual machines by their IDs and the list of the provided IDs contains the IDs of removed virtual machines, Get-VM returns no value.


      On vCenter Server 5.0,


    returns a result even if you pass a hashtable with inapplicable elements.


  • The LocalPath parameter set of Install-VMHostPatch does not work.
  • Install-VMHostPatch cannot install patches on diskless ESXi servers.
  • Install-VMHostPatch cannot install patches on ESX 3.5.
  • Install-VMHostPatch cannot apply VIB patches.
    Workaround: Use metadata.zip patches.


      When using


    to invoke multi-line BAT and BASH scripts, the command might not run all the script lines.



    does not ask for confirmation when you try to create a VMDK anti-affinity rule that overwrites an existing one.


      Cloning a server-side customization specification with


      changes the values of the


      properties from






      If you use


      to create a permission for a distributed switch, the


      property of the returned object is





    cannot configure the MAC address on VirtualCenter Server 2.5 and ESX 3.5 hosts.



    cannot set an annotation for a custom attribute if another custom attribute with the same name exists.


      Increasing the size of a system partition on Windows 7 and Windows 2008 by using the


      parameter of


    is not supported.



      disconnects the vCenter Server if the name you pass to the


    parameter already exists for another resource pool on the server.

Set-ScsiController (added to ref)


      cannot set both the




      parameters at the same time.


    Workaround: First run the cmdlet to set the type and then run it again to configure the bus sharing mode.








      , and


      parameters of


    do not work on ESX 4.0 and later.


    On vCenter Server 5.0, when you use Set-VM to upgrade the VM hardware version, the output of the cmdlet displays the old value although the version has been updated successfully.


      On Windows operating systems,


    becomes non-responding if the provided IP address conflicts with an existing IP address on the network.



      might not populate the


      property of the returned


      object when




      properties are modified.


      Workaround: Use


      to retrieve the object returned by





      cannot clear the values of the




    properties of the input object.


    If you have vMotion enabled on one VMKernel nic and you enable it on a second nic on the same switch (using Set-VMHostNetworkAdapter), ‘VMotionEnabled’ property of the second nic may still report that vMotion is not enabled. This is due to the fact that there can only be one nic selected for vMotion, but more than one can be ‘candidate’ nics for vMotion. In the described scenario the second nic will become a ‘candidate’ nic for vMotion. If you want to change the currently active vMotion nic – first disable the current one and then enable the one you want.


      Changing the value of the


      parameter to




      changes the value of the


      parameter to


    as well.



    cannot configure correctly the DNS address on Linux operating systems.


  • The default value of the Set-VMHostSNMP TargetPort parameter is a random number instead of the port number.
  • Set-VMHostSNMP skips the value of the TargetPort parameter.
  • Set-VMHostSNMP fails to enable VMHostSNMP and to set the ReadOnlyCommunityString when called for the first time.
    Workaround: Run the command again.

Inventory Provider

      When run within the Inventory Provider,


      returns the datacenters from the default servers instead from the


    folder of the Inventory Provider drive.


    The examples in section “Use ESXCLI with PowerCLI” in the PowerCLI 5.0 User’s Guide, are not applicable to ESX versions later than 4.0.


  • On vCenter Server 5.0/ ESXi 5.0 platforms, all guest-related cmdlets have slow and unstable behavior due to the slow performance of VMware Tools.
  • The VirtualMachine parameter of the PowerCLI cmdlets is defined with the deprecated Description property of the VirtualMachine type, instead of the new one named Notes. In result, The PowerShell auto-complete function works with the deprecated property name.
  • The types labels in the UpdateViewData property are case-sensitive.
  • When running in 64-bit mode, PowerCLI cannot detect the registry key HKEY_LOCAL_MACHINE\SOFTWARE\VMware, Inc.\VMware vSphere PowerCLI\, which is used for determining the PowerCLI installation folder. Instead, you can use the following key: HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\VMware, Inc.\VMware vSphere PowerCLI.
  • The Model and Vendor properties of the ScsiLun objects are always filled up with white-spaces to 16 (for Model) and 8 (for Vendor) characters.
  • All VIX cmdlets support using SSPI for Windows guest machines if the underlying vCenter Server is 5.0 version. This might not be valid for users who are local, and not domain users. VIX cmdlets are Invoke-VMScript, Copy-VMGuestFile, *-VMGuestNetworkInterface, *-VMGUestRoute, and Set-HardDisk when used for guest disk resizing.

Resolved Issues

The following issues have been resolved in vSphere PowerCLI 5.0:


  • If a ManagedObjectReference object that points to StorageResourceManager is specified for the Id parameter, Get-View returns no result.
  • Get-View fails to retrive Cluster views if HA is enabled.



    throws an error if there is a disconnected network adapter.


      On Windows operating systems, the


      property of the objects returned by


    is incorrect.


  • On 64-bit operating systems, Invoke-VMScript works only in 32-bit mode.
  • Invoke-VMScript does not work if the guest operating system is installed on a drive other than C: or D:.
  • Running Invoke-VMScript against outdated VMware Tools might make the console non-responsive.
  • Invoke-VMScript might become non-responding.


  • New-OSCustomizationSpec clones only the first object if an array of objects is provided.
  • VMware vClient shows an error message Error reading password when opening specifications that are created by New-OSCustomizationSpec with empty passwords.


      When run with the


      switch parameter set to




      creates a snapshot with


      property set to




  • Set-HardDisk fails to resize the hard disk, if the helper virtual machine cannot access the datastore where the target hard disk is located.
  • Set-HardDisk fails to resize the hard disk, if the power state of the helper virtual machine is powered on.
    Workaround: Refresh the helper virtual machine object before running Set-HardDisk.



    does not set a persistent proxy policy.


  • Set-VM cannot modify the DrsAutomationLevel property of the virtual machine if the current value of the property is Disabled.
  • Set-VM accepts only values that are powers of 2 for the Numcpu parameter.


  • On Linux Red Hat 5, Set-VMGuestNetworkInterface cannot set static DNS addresses.
  • Set-VMGuestNetworkInterface cannot set the WinsPolicy property to dhcp.


      On Linux operating systems,


      cannot modify routes.


    Workaround: Remove all guest routes and then add them one by one.



      cannot configure



vSphere SDK for .NET



      property of the


    object is not populated.

Installing vSphere PowerCLI

VMware provides a single installer for vSphere PowerCLI.

To install vSphere PowerCLI

  1. Download vSphere PowerCLI 5.0.
  2. Launch the vSphere PowerCLI installer by double-clicking the executable file. In the Welcome page, click Next.
  3. To install vSphere PowerCLI in a non-default location, click Change in the Destination Folder page and select a different directory.
  4. In the Ready to Install the Program page, choose whether to create a desktop shortcut.
  5. Click Install to proceed with the installation.
  6. Click Finish to complete the installation process.

Source : VMware

PowerCLI v5 is available, download it NOW!

Run, don’t walk to vmware.com/go/powercli to grab the latest version of the world’s best PowerShell snapin. That’s right, v5 is out and you can grab it now! And the coolest part is that while nobody will have vSphere 5 in production on day one (ok, there’s a couple of you out there), PowerCLI v5 is a client-based tool with no dependencies, and it’s downwards-compatible! There is literally no reason for you not to upgrade right this instant! I am using exclamations here, people!

I’ve had beta builds installed for some time, but I didn’t want to do blog posts based on pre-release builds for fear that things would change. Now that it’s out, I’ll start pushing out some posts about what’s new and all that, so stay tuned. For now, some quick stats and info:

There are now FOUR VMware snap-ins installed with PowerCLI v5:

PowerCLI U:\> Get-PSSnapin vmware*

Name        : VMware.VimAutomation.Core
PSVersion   : 2.0
Description : This Windows PowerShell snap-in contains Windows PowerShell cmdlets for managing vSphere.

Name        : VMware.VimAutomation.License
PSVersion   : 2.0
Description : This Windows Powershell snap-in contains cmdlets for managing License components.

Name        : VMware.DeployAutomation
PSVersion   : 2.0
Description : Cmdlets for Rule-Based-Deployment

Name        : VMware.ImageBuilder
PSVersion   : 2.0
Description : This Windows PowerShell snap-in contains VMware ESXi Image Builder cmdlets used to generate custom images.

There are 293 cmdlets in total across these snap-ins. Here they are, grouped by Noun and Verb:

PowerCLI U:\> $c = Get-Command -Module vmware*
PowerCLI U:\> $c.Length
PowerCLI U:\> $c | group verb

Count Name                      Group
—– —-                      —–
6 Add                       {Add-DeployRule, Add-EsxSoftwareDepot, Add-E…
3 Apply                     {Apply-DrsRecommendation, Apply-ESXImageProf…
1 Compare                   {Compare-EsxImageProfile}
1 Connect                   {Connect-VIServer}
4 Copy                      {Copy-DatastoreItem, Copy-DeployRule, Copy-H…
1 Disconnect                {Disconnect-VIServer}
1 Dismount                  {Dismount-Tools}
3 Export                    {Export-EsxImageProfile, Export-VApp, Export…
1 Format                    {Format-VMHostDiskPartition}
95 Get                       {Get-AdvancedSetting, Get-AlarmAction, Get-A…
2 Import                    {Import-VApp, Import-VMHostProfile}
1 Install                   {Install-VMHostPatch}
1 Invoke                    {Invoke-VMScript}
1 Mount                     {Mount-Tools}
9 Move                      {Move-Cluster, Move-Datacenter, Move-Folder,…
37 New                       {New-AdvancedSetting, New-AlarmAction, New-A…
42 Remove                    {Remove-AdvancedSetting, Remove-AlarmAction,…
2 Repair                    {Repair-DeployImageCache, Repair-DeployRuleS…
4 Restart                   {Restart-VM, Restart-VMGuest, Restart-VMHost…
58 Set                       {Set-AdvancedSetting, Set-AlarmDefinition, S…
1 Shutdown                  {Shutdown-VMGuest}
4 Start                     {Start-VApp, Start-VM, Start-VMHost, Start-V…
5 Stop                      {Stop-Task, Stop-VApp, Stop-VM, Stop-VMHost…}
3 Suspend                   {Suspend-VM, Suspend-VMGuest, Suspend-VMHost}
1 Switch                    {Switch-ActiveDeployRuleSet}
3 Test                      {Test-DeployRuleSetCompliance, Test-VMHostPr…
1 Update                    {Update-Tools}
2 Wait                      {Wait-Task, Wait-Tools}

PowerCLI U:\> $c | group noun

Count Name                      Group
—– —-                      —–
6 DeployRule                {Add-DeployRule, Copy-DeployRule, Get-Deploy…
2 EsxSoftwareDepot          {Add-EsxSoftwareDepot, Remove-EsxSoftwareDepot}
3 EsxSoftwarePackage        {Add-EsxSoftwarePackage, Get-EsxSoftwarePack…
3 PassthroughDevice         {Add-PassthroughDevice, Get-PassthroughDevic…
9 VMHost                    {Add-VMHost, Get-VMHost, Move-VMHost, Remove…
3 VmHostNtpServer           {Add-VmHostNtpServer, Get-VMHostNtpServer, R…
2 DrsRecommendation         {Apply-DrsRecommendation, Get-DrsRecommendat…
6 ESXImageProfile           {Apply-ESXImageProfile, Compare-EsxImageProf…
7 VMHostProfile             {Apply-VMHostProfile, Export-VMHostProfile, …
2 VIServer                  {Connect-VIServer, Disconnect-VIServer}
1 DatastoreItem             {Copy-DatastoreItem}
5 HardDisk                  {Copy-HardDisk, Get-HardDisk, New-HardDisk, …
1 VMGuestFile               {Copy-VMGuestFile}
4 Tools                     {Dismount-Tools, Mount-Tools, Update-Tools, …
9 VApp                      {Export-VApp, Get-VApp, Import-VApp, Move-VA…
2 VMHostDiskPartition       {Format-VMHostDiskPartition, Get-VMHostDiskP…
4 AdvancedSetting           {Get-AdvancedSetting, New-AdvancedSetting, R…
3 AlarmAction               {Get-AlarmAction, New-AlarmAction, Remove-Al…
3 AlarmActionTrigger        {Get-AlarmActionTrigger, New-AlarmActionTrig…
2 AlarmDefinition           {Get-AlarmDefinition, Set-AlarmDefinition}
2 Annotation                {Get-Annotation, Set-Annotation}
4 CDDrive                   {Get-CDDrive, New-CDDrive, Remove-CDDrive, S…
5 Cluster                   {Get-Cluster, Move-Cluster, New-Cluster, Rem…
4 CustomAttribute           {Get-CustomAttribute, New-CustomAttribute, R…
5 Datacenter                {Get-Datacenter, Move-Datacenter, New-Datace…
4 Datastore                 {Get-Datastore, New-Datastore, Remove-Datast…
1 DatastoreCluster          {Get-DatastoreCluster}
2 DeployRuleSet             {Get-DeployRuleSet, Set-DeployRuleSet}
4 DrsRule                   {Get-DrsRule, New-DrsRule, Remove-DrsRule, S…
1 ErrorReport               {Get-ErrorReport}
1 EsxCli                    {Get-EsxCli}
1 EsxSoftwareChannel        {Get-EsxSoftwareChannel}
1 EsxTop                    {Get-EsxTop}
4 FloppyDrive               {Get-FloppyDrive, New-FloppyDrive, Remove-Fl…
5 Folder                    {Get-Folder, Move-Folder, New-Folder, Remove…
1 HAPrimaryVMHost           {Get-HAPrimaryVMHost}
3 Inventory                 {Get-Inventory, Move-Inventory, Remove-Inven…
4 IScsiHbaTarget            {Get-IScsiHbaTarget, New-IScsiHbaTarget, Rem…
1 LicenseDataManager        {Get-LicenseDataManager}
1 Log                       {Get-Log}
1 LogType                   {Get-LogType}
4 NetworkAdapter            {Get-NetworkAdapter, New-NetworkAdapter, Rem…
2 NicTeamingPolicy          {Get-NicTeamingPolicy, Set-NicTeamingPolicy}
4 OSCustomizationNicMapping {Get-OSCustomizationNicMapping, New-OSCustom…
4 OSCustomizationSpec       {Get-OSCustomizationSpec, New-OSCustomizatio…
2 PowerCLIConfiguration     {Get-PowerCLIConfiguration, Set-PowerCLIConf…
1 PowerCLIVersion           {Get-PowerCLIVersion}
5 ResourcePool              {Get-ResourcePool, Move-ResourcePool, New-Re…
3 ScsiController            {Get-ScsiController, New-ScsiController, Set…
2 ScsiLun                   {Get-ScsiLun, Set-ScsiLun}
2 ScsiLunPath               {Get-ScsiLunPath, Set-ScsiLunPath}
4 Snapshot                  {Get-Snapshot, New-Snapshot, Remove-Snapshot…
1 Stat                      {Get-Stat}
4 StatInterval              {Get-StatInterval, New-StatInterval, Remove-…
1 StatType                  {Get-StatType}
3 Task                      {Get-Task, Stop-Task, Wait-Task}
5 Template                  {Get-Template, Move-Template, New-Template, …
2 UsbDevice                 {Get-UsbDevice, Remove-UsbDevice}
1 VIAccount                 {Get-VIAccount}
3 VICredentialStoreItem     {Get-VICredentialStoreItem, New-VICredential…
1 VIEvent                   {Get-VIEvent}
1 View                      {Get-View}
1 VIObjectByVIView          {Get-VIObjectByVIView}
4 VIPermission              {Get-VIPermission, New-VIPermission, Remove-…
1 VIPrivilege               {Get-VIPrivilege}
3 VIProperty                {Get-VIProperty, New-VIProperty, Remove-VIPr…
4 VIRole                    {Get-VIRole, New-VIRole, Remove-VIRole, Set-…
4 VirtualPortGroup          {Get-VirtualPortGroup, New-VirtualPortGroup,…
4 VirtualSwitch             {Get-VirtualSwitch, New-VirtualSwitch, Remov…
9 VM                        {Get-VM, Move-VM, New-VM, Remove-VM…}
4 VMGuest                   {Get-VMGuest, Restart-VMGuest, Shutdown-VMGu…
2 VMGuestNetworkInterface   {Get-VMGuestNetworkInterface, Set-VMGuestNet…
3 VMGuestRoute              {Get-VMGuestRoute, New-VMGuestRoute, Remove-…
4 VMHostAccount             {Get-VMHostAccount, New-VMHostAccount, Remov…
2 VMHostAdvancedConfigur… {Get-VMHostAdvancedConfiguration, Set-VMHost…
1 VMHostAttributes          {Get-VMHostAttributes}
2 VMHostAuthentication      {Get-VMHostAuthentication, Set-VMHostAuthent…
1 VMHostAvailableTimeZone   {Get-VMHostAvailableTimeZone}
2 VMHostDiagnosticPartition {Get-VMHostDiagnosticPartition, Set-VMHostDi…
1 VMHostDisk                {Get-VMHostDisk}
2 VMHostFirewallDefaultP… {Get-VMHostFirewallDefaultPolicy, Set-VMHost…
2 VMHostFirewallException   {Get-VMHostFirewallException, Set-VMHostFire…
2 VMHostFirmware            {Get-VMHostFirmware, Set-VMHostFirmware}
2 VMHostHba                 {Get-VMHostHba, Set-VMHostHba}
1 VMHostImageProfile        {Get-VMHostImageProfile}
1 VMHostMatchingRules       {Get-VMHostMatchingRules}
2 VMHostModule              {Get-VMHostModule, Set-VMHostModule}
2 VMHostNetwork             {Get-VMHostNetwork, Set-VMHostNetwork}
4 VMHostNetworkAdapter      {Get-VMHostNetworkAdapter, New-VMHostNetwork…
2 VMHostPatch               {Get-VMHostPatch, Install-VMHostPatch}
1 VMHostProfileRequiredI… {Get-VMHostProfileRequiredInput}
4 VMHostRoute               {Get-VMHostRoute, New-VMHostRoute, Remove-VM…
5 VMHostService             {Get-VMHostService, Restart-VMHostService, S…
3 VMHostSnmp                {Get-VMHostSnmp, Set-VMHostSnmp, Test-VMHost…
2 VMHostStartPolicy         {Get-VMHostStartPolicy, Set-VMHostStartPolicy}
2 VMHostStorage             {Get-VMHostStorage, Set-VMHostStorage}
2 VMHostSysLogServer        {Get-VMHostSysLogServer, Set-VMHostSysLogSer…
2 VMQuestion                {Get-VMQuestion, Set-VMQuestion}
2 VMResourceConfiguration   {Get-VMResourceConfiguration, Set-VMResource…
2 VMStartPolicy             {Get-VMStartPolicy, Set-VMStartPolicy}
1 VMScript                  {Invoke-VMScript}
3 CustomField               {New-CustomField, Remove-CustomField, Set-Cu…
1 DeployImageCache          {Repair-DeployImageCache}
2 DeployRuleSetCompliance   {Repair-DeployRuleSetCompliance, Test-Deploy…
1 ActiveDeployRuleSet       {Switch-ActiveDeployRuleSet}
1 VMHostProfileCompliance   {Test-VMHostProfileCompliance}


Components of High Availability

Components of High Availability

The first and probably the most important is VPXA. This is not an HA agent, but it is the vCenter agent and it allows your vCenter Server to interact with your ESX host. It is also takes care of stopping and starting virtual machines if and when needed.
HA is loosely coupled with vCenter Server. Although HA is configured by vCenter Server, it does not need vCenter to manage an HA failover. It is comforting to know that in case of a host failure containing the virtualized vCenter server, HA takes care of the failure and restarts the vCenter server on another host, including all other configured virtual machines from that failed host.

When a virtual vCenter is used we do however recommend setting the correct restart priorities within HA to avoid any dependency problems.

It’s highly recommended to register ESX hosts with their FQDN in vCenter. VMware vCenter supplies the name resolution information that HA needs to function. HA stores this locally in a file called “FT_HOSTS”. In other words, from an HA perspective there is no need to create local host files and it is our recommendation to avoid using local host files. They are too static and will make troubleshooting more difficult.

To stress my point even more as of vSphere 4.0 Update 1 host files (i.e. /etc/hosts) are corrected automatically by HA. In other words if you have made a typo or for example forgot to add the short name HA will correct the host file to make sure nothing interferes with HA.

Basic design principle:
Avoid using static host files as it leads to inconsistency, which makes troubleshooting difficult.

VMAP Plug-In

Next on the list is VMAP. Where vpxa is the process for vCenter to communicate with the host VMAP is the translator for the HA agent (AAM) and vpxa. When vpxa wants to communicate with the AAM agent VMAP will translate this into understandable instructions for the AAM agent. A good example of what VMAP would translate is the state of a virtual machine: is it powered on or powered off? Pre-vSphere 4.0 VMAP was a separate process instead of a plugin linked into vpxa. VMAP is loaded into vpxa at runtime when a host is added to an HA cluster.

The vpxa communicates with VMAP and VMAP communicates with AAM. When AAM has received it and flushed the info it well tell VMAP and VMAP on its turn will acknowledge to vpxa that info has been processed. The VMAP plug-in acts as a proxy for communication to AAM.

One thing you are probably wondering is why do we need VMAP in the first place? Wouldn’t this be something vpxa or AAM should be able to do? The answer is yes, either vpxa or AAM should be able to carry this functionality. However, when HA was first introduced it was architecturally more prudent to create a separate process for dealing with this which has now been turned into a plugin.


That brings us to our next and final component, the AAM agent. The AAM agent is the core of HA and actually stands for “Automated Availability Manager”. As stated above, AAM was originally developed by Legato. It is responsible for many tasks such as communicating host resource information, virtual machine states and HA properties to other hosts in the cluster. AAM stores all this info in a database and ensures consistency by replicating this database amongst all primary nodes. (Primary nodes are discussed in more detail in chapter 4.) It is often mentioned that HA uses an In-Memory database only, this is not the case! The data is stored in a database on local storage or in FLASH memory on diskless ESXi hosts.

One of the other tasks AAM is responsible for is the mechanism with which HA detects isolations/failures: heartbeats.
All this makes the AAM agent one of the most important processes on an ESX host, when HA is enabled of course, but we are assuming for now it is. The engineers recognized the importance and added an extra level of resiliency to HA. The agent is multi-process and each process acts as a watchdog for the other. If one of the processes dies the watchdog functionality will pick up on this and restart the process to ensure HA functionality remains without anyone ever noticing it failed. It is also resilient to network interruptions and component failures. Inter-host communication automatically uses another communication path (if the host is configured with redundant management networks) in the case of a network failure. The underlying message framework exactly-once guarantees message delivery.

HA Firewall Requirements

The following list contains the ports that are used by HA for communication. If your environment contains firewalls ensure these ports are opened for HA to function correctly.

High Availability port settings:

8042 – UDP – Used for host-to-hosts “backbone” (message bus) communication
. 8042 – TCP – Used by AAM agents to communicate with a remote backbone
. 8043 – TCP – Used to locate a backbone at bootstrap time
. 8044 – UDP – Used by HA to send heartbeats
. 2050 – 2250 – Used by AAM agent process to communicate with the backbone.