Just a short blog post about Microsoft Exchange 2010 in combination with VMware vMotion. We are running this combination hosted on vSphere platform and noticed that whenever we vMotion over a Exchange 2010 Mailbox server that is using DAG (Database Availability Group’s), the DAG will fail.
25-05-2011 Update for Exchange 2010 SP1: Thanks to Toti for pointing this out to me, Exchange 2010 SP1 does support vMotion with DAG.
I’m not an Exchange guru but in short this is what the Database Availability Groups look like. The green databases are active and the blue databases are the passive databases which are spread across the rest of the mailbox servers.
Anyway, the story behind the failing DAG is because the DAG is relying on Windows Failover Clustering which doesn’t work and more important, isn’t supported with vMotion (Same counts for Microsoft Hyper-V Live Migration)
VMware’s Setup for Failover Clustering and Microsoft Cluster Service manual states:
Before you set up MSCS, review the list of functionality that is not supported for this release, and any
requirements and recommendations that apply to your configuration.
The following environments and functionality are not supported for MSCS setups with this release of vSphere:
– Clustering on iSCSI or NFS disks.
– Mixed environments, such as configurations where one cluster node is running a different version of
ESX/ESXi than another cluster node.
– Clustered virtual machines as part of VMware clusters (DRS or HA).
– Use of MSCS in conjunction with VMware Fault Tolerance.
– Migration with VMotion of clustered virtual machines.
I knew that Microsoft Cluster wasn’t supported with vMotion but when I heard about the Database Availability Group it didn’t ring a bell for me since I didn’t do any fancy stuff on the VM definition like shared RDM’s and SCSI Bus Sharing.
So to be honest for me this VM was just like the others with the remark that we disabled this VM from participating in DRS and HA because of the Exchange 2010 design.
That brings us to the next unsupported thing that is stated in the VMware Manual: Clustered virtual machines as part of VMware clusters (DRS or HA).
I was assuming that if we manually disabled a VM from participating in a DRS/HA cluster we were running a supported scenario until I contacted Duncan Epping this morning while reading his blog about vSphere Update 1
vSphere Update 1 states:
Enhanced Clustering Support for Microsoft Windows – Microsoft Cluster Server (MSCS) for Windows 2000 and 2003 and Windows Server 2008 Failover Clustering is now supported on an VMware High Availability (HA) and Dynamic Resource Scheduler (DRS) cluster in a limited configuration. HA and DRS functionality can be effectively disabled for individual MSCS virtual machines as opposed to disabling HA and DRS on the entire ESX/ESXi host
Manually disabling a VM from participating in a DRS/HA cluster like I did apparently isn’t a supported configuration! If you want to do this you need vSphere Update 1.
20-07-2010 Update for vSphere 4.1: The new features of vSphere 4.1 are stating:
Windows Failover Clustering with VMware HA. Clustered Virtual Machines that utilize Windows Failover Clustering/Microsoft Cluster Service are now fully supported in conjunction with VMware HA. See Setup for Failover Clustering and Microsoft Cluster Service.