Adding an instance to a SQL 2k5/Win 2k3 cluster - can I use the same disk resources?

  • One of the instances I maintain is a SQL 2005 (Standard, 64-bit, SP2) installation on a 2-node Windows 2003 R2 (Enterprise) cluster, using SAN disk for storage. We're standing up Office Communication Server, and MS' requirements include a dedicated SQL instance. And, since we just doubled the CPU count and RAM in the cluster, we'd like to put it there.

    But I've so far failed to get a definitive answer regarding the SAN disk. Specifically, can two clustered SQL Server instances use the same set of disks? In our case, we've got five (physically) independent sets of disk, for data, log, tempdb, system, and maintenance. While I'm sure it's preferential from a performance standpoint to use separate disks for the new instance, that's going to be difficult to provision out of our current SAN (and I think our storage guy is getting sick of my demand for dedicated spindles...).

    So, is it possible to install a second instance utilizing the same SAN disk? Or do I need new LUNs provisioned?

    Thanks in advance!

    ______
    Twitter: @Control_Group

  • Matt Cherwin (9/10/2009)


    One of the instances I maintain is a SQL 2005 (Standard, 64-bit, SP2) installation on a 2-node Windows 2003 R2 (Enterprise) cluster, using SAN disk for storage. We're standing up Office Communication Server, and MS' requirements include a dedicated SQL instance. And, since we just doubled the CPU count and RAM in the cluster, we'd like to put it there.

    But I've so far failed to get a definitive answer regarding the SAN disk. Specifically, can two clustered SQL Server instances use the same set of disks? In our case, we've got five (physically) independent sets of disk, for data, log, tempdb, system, and maintenance. While I'm sure it's preferential from a performance standpoint to use separate disks for the new instance, that's going to be difficult to provision out of our current SAN (and I think our storage guy is getting sick of my demand for dedicated spindles...).

    So, is it possible to install a second instance utilizing the same SAN disk? Or do I need new LUNs provisioned?

    Thanks in advance!

    It is best practise to have it separate, but i cannot see why you couldnt use the same disks, as long as you set up the dependencies correctly you should be ok.

    hmm might have to reconsider that, seen that most people doent recommend it. and they mention separate disks/luns for each instance. You are aware that you will have to take memory throttling into consideration if you are going to run multiple instances. as well as cpu.

    just out of curiosity is your cluster active active or active passive

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  • Active/Passive. If it turns out we have no choice but to dedicate new LUNs to the OCS instance, I'll probably change it to Active/Active (since it would be separately licensed, anyway). But that really is a last resort (we're real close to out of SAN resources, and since we're looking to ditch our EMC gear soon, we're not terribly interested in adding new hardware right now).

    You're right, though - all the recommendations seem to be against disk sharing, which is why I'm sort of leery. But I've so far failed to find anything definitive (i.e., something I can show to management to justify acquiring more SAN resources).

    ______
    Twitter: @Control_Group

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