SQL Server 2008 R2 Clustering inside VMware

Question

I am working on a new Windows 2008 R2 / SQL Server R2 HA cluster and we are planning on running this inside of VMware ESX 5. I have read and heard differing views on using SQL clustering inside of ESX, some seems to say its fine others do not. We will be running dedicated Hosts, SAN and networking for this as we are very SQL heavy for our core apps, I would like to hear peoples view on if this is a good or bad idea.

Answer 1

We're currently doing this in production with few issues.

VMware has a KB article on virtual MSCS configurations:

http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1004617

Check the appropriate clustering guide PDF for your vSphere version. In particular, pay attention to the support matrices if you're clustering across hosts. Note the following things:

• Only FC shared storage is supported by VMware for usage inside of MSCS (Microsoft may support iSCSI when connected via the guest iSCSI initiator; I'm not positive of this from an MS support perspective)
• Shared virtual disks are not supported when clustering across physical hosts; you must use an RDM (physical mode is recommended)
• You cannot vMotion a node in an MSCS cluster (so disable DRS for these VMs in your cluster configuration)

Also take note of the other setup limitations in the guide. Configuration is fairly straightforward if you follow their directions.

Answer 2

This site is about fact not opinions but I do exactly what you want to do all the time, not in production, I use tin for that, but for test/dev environments it works absolutely great. There's a number of different ways of doing it, we use FC-based RDMs but there are other ways - either way it work, can be a tricky to setup first time, but stays working and as long as you're not too resource limited performs well too. Hope this helps.

Answer 3

I've done this for a lightly-used db instance that backed some fairly simple websites. The main issue I had was getting the iSCSI settings all correct - I ended up using the vSphere iSCSI client and then just mapping the LUNs to the VMs.

That said, we've got some new applications being deployed in the new year that will significantly increase the IO requirements on the database. Therefore, I'm going to be moving the cluster off the virtualised environment and onto dedicated hardware with either HW iSCSI cards or FC (not yet decided / costed). Virtualisation brings some great benefits, but can also bring a whole layer of complications, especially around performance.

If you've got the kit / budget and it's a production instance, I'd run anything other than a very lightly loaded SQL cluster directly on hardware. If it's a dev/test environment, I tend to skip the cluster aspect and run a single SQL instance as a VM.