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volume group lun sizes and no of file systems for optimal performance

  • 1.  volume group lun sizes and no of file systems for optimal performance

    Posted Thu February 03, 2011 02:23 PM

    Originally posted by: smashingpumpkin


    Hello,

    I'm new to this forum, but it looks like a good source of information.

    It's been a while since I've done AIX, but I'm planning
    a new TSM on AIX disk-only backup solution.

    I'm planning to make an AIX volume group out of 40 luns of 1 TB.
    I'm planning to create one big file system on here.
    The purpose for this is to use this as a device class FILE for a TSM disk-only backup solution.

    My question is,
    would it make any difference, performance-wise, if I split up this capacity over multiple file systems, or even multiple VG's ?

    rightnow this is the plan:
    • volume group: VG_TSMFILECLASS -> 40 luns of 1TB
    -> one filesystem on there /FILECLASS/ -> 40 TB
    • device class FILE has /FILECLASS/ specified as directory to work in (at TSM level)
    (all backup data will be written to the same file system and VG)

    would this be better?
    • volume group: VG_TSMFILECLASS -> 40 luns of 1TB
    -> two filesystems on here: /FILECLASS1/ -> 20 TB
    /FILECLASS2/ -> 20 TB
    • device class FILE has /FILECLASS1/ + /FILECLASS2/ specified as diectories to work in
    (when you specify multiple directories for a device class file in TSM, it spreads its volumes in
    a balanced way over the directories that you specify,
    so in this case the backups would be landing on 2 different filesystems in the same VG)

    would this be even better ?
    • volume group: VGTSMFILECLASS1 -> 20 luns of 1 TB
    -> one FILESYSTEM on here: /FILECLASS1/
    • volume group: VGTSMFILECLASS2 -> 20 luns of 1 TB
    -> one FILESYSTEM on here: /FILECLASS2/
    • device class FILE has /FILECLASS1/ + /FILECLASS2/ specified as diectories to work in
    (when you specify multiple directories for a device class file in TSM, it spreads it volumes in
    a balanced way over the directories that you specify,
    so in this case the backups would be landing on 2 different VG's)

    would this make a difference for performance or might I just as well put everything on one file system in one VG ?

    Also is there some kind of optimal lun size for this (from an AIX OS perspective) ?
    some extra info:
    • I would use JFS2,
    (without DIO since the TSM device class FILE works in a sequential way).

    • all storage is on one dedicated storage box
    (EMC Ax4 with 2TB SATA2 disks)

    any hints/thoughts would be appreciated :)
    #AIX-Forum


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