SQL Server Performance

VM ESX3 HD Configuration

Discussion in 'SQL Server 2005 Performance Tuning for Hardware' started by dropout, Jun 24, 2009.

  1. dropout New Member

    Hi all
    I'm a bit confused. Maybe someone can help me.
    Our IT has two consultans. One for the infrastructure, esp. for the VM ESX. One for the SQL-Server 2008.
    We are planning to buy a new server for SQL and our SQL-Consultant wants to have separate Disk-Arrays for DB, TempDB, Log and OS. But our ESX-Consultant tells me it is better to just make one Array for everything, because the architecture of the ESX handels it anyway like that (even if you have different Disk-Arrays).
    I think the SQL-Consultant is right. Because I believe it must be possible to configure the ESX for more then one disk-array ...
    Can anyone clarify this a bit for me.
    Thx a lot
    Reto E.
  2. melvinlusk Member

    My shop has a fairly large ESX farm with about 300 guest VMs on 6 host, of which 65 are SQL Servers.
    Our ESX guys configured the LUNs on our SAN similar to they way your ESX guy described. There are a number of factors that you'll need to take into consideration.
    How many guest are you planning to run, and how many hosts do you have? If you have a lot of guests, it's going to be very difficult to carve up seperate LUNs for data, tempdb, logs, etc for each guest; and if you use a shared data LUN, tempDB LUN, and log LUN for all guest, you're still going to end up with the situation you're trying to avoid because of all the guest accessing the same LUNs simultaneously.
    You're also going to evaluate the capabilities of your storage; is it SAN based? Does it support aggregate LUNs (which is how ours is configured).
    Regardless of how you configure it, disk contention won't be you're big bottleneck; since these SQL machines are virtual, they'll never get to the point where the speed of the disk are what's holding back your performance.
    Also, ESX is going to restrict your SQL VM to a single datastore, which I *believe* can only reside on a single LUN; I'm not an ESX expert by any means, it just seems that way when fooling around with ESXi on my own time.
    Originally I was very skepticle of virtualizing SQL Servers, but it's worked out extremely well for us. Your mileage may vary. Good luck to you!
  3. dropout New Member

    Thx for your report on your experience.
    I've talked again to our Infrastructure-Consultant and what he means is: that (since we don't use FC) all attached storage goes through the VM iSCSI "emulation". And this would be the bottleneck, where all traffic has to pass through.
    Has anyone any test or experience with that?

Share This Page