2011
04.19

Here’s a few KB articles I found that were released by Microsoft recently that affect Hyper-V farms.

KB2004712: Unable to backup Live Virtual Machines in Server 2008 R2 Hyper-V

“When backing up online Virtual Machines (VMs) using Windows Server Backup or Data Protection Manager 2007 SP1, the backup of the individual Virtual Machine may fail with the following error in the hyperv_vmms Event Log:

No snapshots to revert were found for virtual machine ‘VMName’. (Virtual machine ID 1CA5637E-6922-44F7-B17A-B8772D87B4CF)”.

VM with GPT pass through disk on a Hyper-V cluster with SAS based storage array will cause VM to report “Unsupported Cluster Configuration.”

“When you attach a GPT pass-through disk provided from SAS storage (Serial attached SCSI) array to a highly available virtual machine by using the Hyper-V Manager or Failover Cluster Management Microsoft Management Console (MMC) snap-in, the System Center Virtual Machine Manager 2008 Admin Console lists the status of the virtual machine as "Unsupported Cluster Configuration."

Details on the High Availability section of the VMs Properties in SCVMM are:

Highly available virtual machine <Machinename> is not supported by VMM because the VM uses non-clustered storage. Ensure that all of the files and pass-through disks belonging to the VM reside on highly available storage”.

On a computer with more than 64 Logical processors, you may experience random crashes or hangs

“On a computer which has more than 64 logical processors, you may experience random memory corruption during boot processing. This may result in system instability such as random crashes or hangs.

This problem occurs due to a code defect in the NDIS driver (ndis.sys).

Microsoft is currently investigating this problem, and will post more details when a fix is available.

To work around this issue, reduce the number of processors so that the system has no more than 64 logical processors. For example, disable hyper-threading on the processors”.

The network connection of a running Hyper-V virtual machine may be lost under heavy outgoing network traffic on a computer that is running Windows Server 2008 R2 SP1

“Consider the following scenario:

  • You install the Hyper-V role on a computer that is running Windows Server 2008 R2 Service Pack 1 (SP1).
  • You run a virtual machine on the computer.
  • You use a network adapter on the virtual machine to access a network.
  • You establish many concurrent network connections. Or, there is heavy outgoing network traffic.

In this scenario, the network connection on the virtual machine may be lost. Additionally, the network adapter may be disabled”.

A hotfix is available to let you configure a cluster node that does not have quorum votes in Windows Server 2008 and in Windows Server 2008 R2

“Windows Server Failover Clustering (WSFC) uses a majority of votes to establish a quorum for determining cluster membership. Votes are assigned to nodes in the cluster or to a witness that is either a disk or a file share witness. You can use the Configure Cluster Quorum Wizard to configure the clusters quorum model. When you configure a Node Majority, Node and Disk Majority, or Node and File Share Majority quorum model, all nodes in the cluster are each assigned one vote. WSFC does not let you select the cluster nodes that vote for determining quorum.

After you apply the following hotfix, you can select which nodes vote. This functionality improves multi-site clusters.  For example, you may want one site to have more votes than other sites in a disaster recovery. Without the following hotfix, you have to plan the numbers physical servers that are deployed to distribute the number of votes that you want for each site.”

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