VMware does support many OS and application level clustering on top of the vSphere platform. Some notable systems that are supported are; Exchange, SQL and Oracle.
Aravind Sivaraman wrote:
Some links related to Microsoft Cluster
Ah, thank you, from this clearly what I was told about clustering not being supported at all is not true. So now the next question, is Novell Clustering Services officially supported? All I could find is an old KB article (KB 944) discussing NCS with NetWare and GSX Server. That's definitely not current, either with the OS or the hypervisor. Is there official support for NCS with OES 2 (or OES 11) and ESX/ESXi?
There is no official VMware-side statement that it is supported. That said, does this mean it's unsupported by default? I don't think so. I also haven't seen anything that says any guest clustering not explicitly supported (like Microsoft clustering) is generally unsupported.
Your best bet would be to open a support case with VMware and clarify what exactly you and your clustering solution are going to do. VMware probably will not provide any in-depth troubleshooting within the clustering solution, but as long as the issue is within the realm of normal VM-operations, I don't see any justifyable reason why they should turn you down (which doesn't mean they won't though). After all, for VMware/the hypervisor(s) it's just 2 VMs and some shared disks, with the actual magic being done by some application inside the VMs.
I assume at least limitations like the ones mentioned in the MSCS documents still apply:
Make especially sure Novell supports clustering across VMs on ESXi. RedHat for example openly supports clustering on vSphere: