They do not support the Clustering feature on VMware:

Summary Support Statement*
This configuration is Supported.

* Customers with Premier-level support agreements should contact their account manager for more information
* Additional information is available in the “Support policy for Microsoft software running in non-Microsoft hardware virtualization software” which can be viewed here

Support Statement Details

Product: Windows Server 2003 Service Pack 2 on VMware ESX with Windows Server 2003 SP2 (x86) Guest OS

Search the Knowledge Base for information related to this configuration

vsupport_comment
Supported features:

Unsupported features: Failover Clustering (MSCS)

This make not easy to push the solution to customers even if it works…how would you reply to this ?

Are they saying they do not support it because they just don’t know if it will work????…….. or are there specific issues they encountered with the 64 bit version of W2K3 Server MSCS?

V/R,

Barny,

Are there any particular reasons you try to avoid mscs clustering (of Exchange, for example) in a virtual environment? Are there any significant (technical) drawbacks?

”
Support for Microsoft Cluster Service (MSCS)
VMware ESX Server 3.5 Update 1 supports Microsoft Cluster Service. Support is similar to ESX Server 3.0.1 with the following additions:

- Both 64 bit and 32 bit Windows 2003 guests are supported with MSCS.
- Boot from SAN for VMs using MSCS is now supported.
-Majority Node Set clusters with application-level replication (for example, Exchange 2007 Cluster Continuous Replication (CCR) is now supported.
“

The release notes of ESX server 3.5 from the vmware site are still clear:

“Microsoft Cluster Service (MSCS) is not supported in this release of ESX Server.”

Thx,
Vegeta

In my opinion and experience there’s a down side to both options… Stateful doesn’t provide you with the flexibility VMware can provide you with, and besides that it isn’t completely stateful anyway. In production environment you’ll often see more downtime for stateful clusters than you would expect.

on the other hand, HA will never provide you with stateful clustering… but continous availability will in the feature. so we will just have to wait and see.

For an ESX environment virtual MSCS clustering is something I personally try to avoid.

What if you have an application that required high uptime? What if a VMware host crashed due to hardware failure and your VM was running on it?

HA will start the VM from other VMware host but there will be downtime involved. With MSCS, you can have 2 VMs separated by rules so unless both VMware hosts crash at the same time, you will always have a VM running and with MSCS, it can keep resources available to users.

Thanks,
Bhargav

Just a quick question mate.

Why would an architecture require MSCS if HA/DRS in enabled?

What sort of env variables might dictate MSCS as necessary?

I cannot think of a reason to use MSCS w/ VMware Guest OSs now that HA Clustering has been introduced? Can you mate?

Best regards,
Jason