SQL Server Performance

SAN - 1 vs multiple RAID 10 arrays

Discussion in 'Performance Tuning for Hardware Configurations' started by natnat, Oct 16, 2004.

  1. natnat New Member

    I am planning to install a SAN with 14 15K SCSI disks. This configuration will be used by multiple servers. So far it will be 2 dedicated SQL servers and 1 dedicated application server.

    I have planned to use this RAID configuration:
    RAID0: 10 disks with RAID 10, for random read/write operations. SQL data and OS devices.
    RAID1: 4 disks with RAID 10, for sequential read/write operations. SQL TRN logs and some logs from the applications servers.

    All servers will use the same disk configuration.

    Is it reccomended to use the same disk configuration on all servers, or should I create dedicated RAID devices for each server?
  2. derrickleggett New Member

    I'm not sure what your question is. You can't share those RAID arrays on a SAN with multiple servers. You get one host PER RAID array. What type of a SAN is this? Perhaps, we can give you more guidance then. You also might be confusing RAID Groups with RAID arrays on a standard enclosure. This is a pretty common error.

    MeanOldDBA
    derrickleggett@hotmail.com

    When life gives you a lemon, fire the DBA.
  3. natnat New Member

    This is a Compaq MSA 1500 SAN.

    Possible changes in our plans...
    New configuration:
    Compaq MSA 1500 SAN with 14*36GB 15K disks
    2 DL380 SQL servers (cluster active/passive)
    2 DL380 app servers (cluster active/passive)

    OS: RAID 10 with 4 disks
    SQL data: RAID 10 with 6 disks
    SQL trn: RAID 10 with 4 disks

    All servers share the same physical disks. Is this a recommended RAID/SAN configuration?
  4. satya Moderator

  5. derrickleggett New Member

    What is your application server going to use? How would you do your LUN configuration on this? If you are thinking that you can present each one of those RAID arrays as a single drive, and present that single drive to multiple hosts, you are wrong. That will work for a cluster shared resource.

    In other words, give just a little more detail. What drives will you be assigning to each server? What RAID arrays on the SAN will each one be composed of?

    MeanOldDBA
    derrickleggett@hotmail.com

    When life gives you a lemon, fire the DBA.
  6. natnat New Member

    I'm not going to whare the same partitions on different servers, but I want to use the same physical drives for all servers. Is that possible ?

    My configuration will be:
    OS: RAID 10 with 4 disks. I will create 4 logical drives out of these physical disks, one logical drive for each server.
    SQL data: Raid 10 with 6 disks. One logical drive in active/passive configuration (cluster).
    SQL trn: RAID 10 with 4 disks. 2 logical drives, one for SQL server and one for the application servers (active/passive).

  7. derrickleggett New Member

    Couple tweaks here:

    1. Place the data on 4 RAID 5.
    --You really only have one server in an active/passive SQL Server config.
    --You want the extra disks for the trn and app server.
    2. Place six disks in RAID 10 for the trn and app server.
    3. Even better, if the app is stateless, store the app on the app server drives or use 4 disks for the RAID 10 and a mirrored set for the app.

    MeanOldDBA
    derrickleggett@hotmail.com

    When life gives you a lemon, fire the DBA.
  8. aawara New Member

    I really dont see much of an issue here except that I would prefer data, log and tempdb seperate so to balance the IO. Dont forget your good old friend "TempDB" specially if you will be needing/Using it a lot. It does not really require any fancy RAID solution either.

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