clustered sql servers with virtual machines - Good or Bad!

  • Hi all,

    We have a project meeting regarding the setup of clustered sql servers with virtual machines.

    I have heard this is a bad idea using virtual machines in a production enviroment.

    This is something i am not familure with and would like to know from them of you in the know what your thoughts are.

    and what questions if any I should be asking.

    Thanks

  • This has been hit or miss for a lot of people. I have had good and bad experiences with virtual servers and SQL 2005 and I do not use it in production envrionments.

    The best advice is to test your environment carefully.

    Also, read the licensing agreements relating to hardware virtualization for SQL Server (MS has several documents and they are confusing). Support for virtualized environments is "limited" and only available with certain levels of support. The virtulization software must be in the MS virtualization partner program (the list of them on the MSDN website seems to be constantly shrinking). MS also has the right to tell you to move to a physical environment to assist you in troubleshooting (that is a bit scary).

    On the other hand, you may want to look into Hyper-V. At least any problem is an MS problem.

  • ybol:

    I have used clusters and virtual machines for years. I have not had any problems so far. The disavantages in using cluster is its difficulty in recovery.

    Would you like to share what you know or heard from other people its disavantages?

    Many thanks in advance.

  • Ybol

    the first question has to be

    What virtualisation platform do you intend to use?

    It is not uncommon to have a physical node (active) and a virtual node (passive).

    If using something like VMWare HA then windows clustering is really pointless

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    "Ya can't make an omelette without breaking just a few eggs" 😉

  • Its been a big hit for me. I'm able to drastically reduce operating costs, and provide the same level of service availability and performace. Of course, testing and performance monitoring is essential, but if you're not using a whole lot of processor time and physical memory, and your disk I/O is rather low, it just makes good business sense to virtualize.

    I used to be against this for SQL Server. Now I'm a big fan of it. If you've got a SAN solution that's replicated to your DR site, it REALLY reduces the amount of time to recover, and vastly reduces the cost for your DR site.

  • Perry Whittle (8/8/2008)


    Ybol

    the first question has to be

    What virtualisation platform do you intend to use?

    It is not uncommon to have a physical node (active) and a virtual node (passive).

    If using something like VMWare HA then windows clustering is really pointless

    And oh what an awesome thing VMWare HA is...

  • Jeremy Brown (8/8/2008)


    And oh what an awesome thing VMWare HA is...

    sort of makes MSCS redundant really doesnt it

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    "Ya can't make an omelette without breaking just a few eggs" 😉

  • Perry Whittle (8/8/2008)

    sort of makes MSCS redundant really doesnt it

    Oh yeah... Not to mention the fact that I find it entirely more reliable than MSCS. Show of hands, who's been burned by the real failover scenario where a cluster node fails over in the middle of the night and one of the cluster group resources doesn't spin up on the secondary server for whatever reason? I know I have!

    Oh and not to mention the quirky little issues that seem to persist to this day surrounding MS DTC and SQL Server running on a cluster.

    I mean, yes, I know there's no "perfect" scenario where everything works as designed. But MSCS has certainly had its fair share of "fun" over the years.

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