Results 1 to 5 of 5
  1. #1
    Join Date
    Dec 2007
    Location
    Richmond, VA
    Posts
    1,328
    Provided Answers: 5

    Unanswered: HDISKS for SQLTEMP

    I am trying to get our AIX guys to make some changes to the HDISK placement on some of our DB2 servers and thought I would check with you all for some comparison.
    Currently, they have sqltemp FS defined to a single HDISK on this machine. It is pegged at 100% all the time according to topas -D. I want it spread out over several hdisks and separate from the hdisks that house the DB data. Any other thoughts out there on placement?
    Thanks.
    Dave

  2. #2
    Join Date
    Dec 2007
    Location
    Richmond, VA
    Posts
    1,328
    Provided Answers: 5
    no one spreads their sqltemp directory over multiple disks?
    Dave

  3. #3
    Join Date
    Nov 2011
    Posts
    334
    Hi,
    What is the sqltemp ? Is it temporary tablespaces?

  4. #4
    Join Date
    Feb 2004
    Location
    In front of the computer
    Posts
    15,579
    Provided Answers: 54
    I don't have any DB2 server installations that are running on local disk. The servers all use one form or another of SAN fabric, so devices are managed at that level.

    If you are running local disk for your DB2 storage, then I think that spreading the databases over as many drive spindles as possible is a good idea in general, and since temp space tends to get hit harder with IO than most that means that the temp space is a prime candidate.

    -PatP
    In theory, theory and practice are identical. In practice, theory and practice are unrelated.

  5. #5
    Join Date
    Sep 2007
    Location
    Moscow
    Posts
    41
    IMHO, topas/nmon 'Busy%' metrick is inadequate. I'm never trust it.

    One FC/SAS 15K HDD can handle ~200 iops and ~ 150 MB/s.
    How many BPS/TPS topas show (or 'iostat -d hdiskN' tps ) in your case when Busy%=100% ?

    Ask your AIX guys how many real spindles is behind HDISK/LUN for DB2 DB tempspace filesystem ? Is it on dedicated RAID or colocated with some other LUN's/HDISK's ?

    You can test tempspace filesystem i/o with AIX ndisk64 utility (in direct mode for seqential and random pattern with blocksize equal to database PAGESIZE and EXTENTSIZE) to determine max capabilities of your HDISK.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •