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Can we get away with using RDM for MSCS on a ESX 4.0 host-host active/passive cluster

Hi all,

We are considering an active/passive cluster for our SQL 2008 Standard R2 database server in our remote datacentre. Currently there are two ESX hosts out there so we want to have clustering across hosts incase one fails. The SQL server is running Windows Server 2008 Ent R2. The shared storage is an AMS2100 with SAS  drives. The SAN has built in thin provisioning so LUNs are created from an over-alocated storage pool.

The big question is that we want to use VMFS for the cluster and not RDM if at all possible. This enables easy backup of the Virtual Machine. Can we use VMFS drives only?

Also, if anyone else has been through this I'd like to hear other suggestions on how to provide redundancy for SQL and what you would recommend. Clustering is only a consideration at the moment.

Thanks for your responses.


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Well ... If you have vMotion support in you ESX servers, it's a far better/easier way to protect yourself from a failing ESX host.

What exacly do you want to protect yourself from?

By the way, it's not recommended to run SQL Server in a VM if you're goingto put any significant load it. It will have IO problems.
You need this reference document: http://www.vmware.com/pdf/vsphere4/r40_u1/vsp_40_u1_mscs.pdf

Look at the section on clustering virtual machines across physical hosts -- you will need RDMs set up.

Sorry for the bad news - Good Luck

As far as recommendations - my remote SQL for my DR environment is NOT in a MSCS cluster - instead I depend on VMware's HA for SQL availability. It is also on a Hitachi AMS2100 utilizing wide striping (raid 5), and I use VMFS datastores for database and log. If I was really concerned about performance I would use raid 10 for logs...

In my shop SQL does not sustain a very high I/O load as most of my database work is on Oracle RAC clusters across physical machines.

For more info on performance of SQL on VMware as opposed to running on physical machines take a look at the whitepaper http://www.vmware.com/files/pdf/perf_vsphere_sql_scalability.pdf 

Performance and Scalability of Microsoft® SQL Server® on VMware vSphere™ 4

Good Luck
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