Posts Tagged ‘Hyper-V’

Cluster Aware Updating Role Install Failure

March 22nd, 2013

“Unable to create the CAU clustered role because a Network Name resource could not be created. This can occur if a computer account (virtual computer object) for the role could not be created in the domain. Check the event log for more information. If the cluster name account does not have permissions to create the object, you can pre-stage a computer account in Active Directory. Then, use the Add-CauClusterRole Windows PowerShell cmdlet with the VirtualComputerObjectName parameter to create the CAU clustered role. For more information about pre-staging computer accounts, see”

When the CAU role is installed, it attempts to create a computer object in the same OU as the Cluster computer object. Even though you are logged in as a Domain Admin, it will fail because the Cluster Computer object is what is attempting to create the new object, not your user. The resolution for this is to add permissions to the OU containing the Cluster computer object so that it can create the new object.

1. Open up Active Directory Users and Computers, go to View and select Advanced Features.
2. Navigate to the OU where your cluster object resides and right-click on the folder and choose properties.
3. Go to the Security tab. Add your Hyper-V cluster computer object, then choose Advanced.
4. From there select your Hyper-V cluster object and choose Edit. Navigate down to “Create Computer objects” and check the check box.
5. Re-run the powershell command or CAU Wizard to enable the role.

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Server 2008 with Hyper-V Hangs after login or startup for an extended period of time then resumes normal operation.

April 19th, 2012

I recently ran into an issue where my 2008 Hyper-V hosts would reboot, get to the login prompt then after the login prompt either hang at the welcome screen or login fine and operate normally for a minute or two then lock up for 30-45 minutes. If I had enough time to start the virtual machines on the box, they would run fine in the background, you just could not do anything on the console or login remotely to the machine.  You could ping and connect to the file system remotely but that was the extent of the remote services available.

After searching long and hard to find a solution I ran across the following blog which explained my exact problem:

I run NetBackup and leverage VSS snapshots for backups.  These 2008 boxes have been in commission for quite a while and have amassed 3-4K orphaned devices.

There is an 2008 R2 hotfix out there for this issue:

However this hotfix does not install on 2008 R1. I had to track down the DevNodeClean utility which Microsoft does not distribute. I found and tested this on a test server which worked great.


DevNodeClean Utility Instructions:

Usage: DevNodeClean /r /l /?

/r displays removes the phantom device nodes. Otherwise only shows what will be removed
/l displays all device nodes including non-phantom. Does not remove unless -r is also included.
(Only phantom devices are ever removed.)
/? displays this help screen

Must be run as administrator
Backup and Restore privileges are required to run this utility.

Download:   DevNodeClean-x64   or  DevNodeClean-x32

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Permissions on Hyper-V virtual machine files.

April 16th, 2012

If for some reason you move your VHD files or virtual machine files manually this might break the security permissions.  Each VM has a unique ID/Account that must have access to the virtual machine files, the vhd and any other related files to that virtual machine.  The statements below will allow you to restore permissions on the link to your virtual machine as well as your virtual machine files.  You will want to substitute the ID for the ID of your machine that is displayed in the error message you are getting when trying to start your virtual machine.

This statement corrects permissions on the link:
icacls "%SYSTEMDRIVE%\ProgramData\Microsoft\Windows\Hyper-V\Virtual Machines\A263BAED-FCE8-4E9C-9611-C2397459F849.xml" /grant "NT VIRTUAL MACHINE\A263BAED-FCE8-4E9C-9611-C2397459F849":F /l


This corrects permissions on the vhd, and all other files if they are contained in one folder structure.  You will want to change the drive/folder paths as neccesary for your installation.
icacls "F:\ProgramData\Microsoft\Windows\Hyper-V\foo\*" /grant "NT VIRTUAL MACHINE\A263BAED-FCE8-4E9C-9611-C2397459F849":(OI)(CI)F

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