Results 1 to 3 of 3
  1. #1
    Join Date
    May 2004
    Location
    New York
    Posts
    248

    Unanswered: performance issues

    Hi, trying to tune some of the performance issues on a HP box running Informix 7.3 UC3.

    LRU's are set at 1 and 2 but the checkpoint are taking about 4-5 seconds on the average, and output of onstat -F shows that the system is doing most of the flushing at checkpoints, any Ideas on how to force it to do more LRU writes?
    here are some of the values

    MULTIPROCESSOR 1
    NUMCPUVPS 4

    BUFFERS 100000
    NUMAIOVPS 5
    CLEANERS 6
    LRUS 6



    onstat -p
    the percent read cache is about 95 and write cache is about 80

    I'm thinking about increasing the LRUS and the CLEANERS

    Any suggestions on this?

    System disk is being hammered pretty often, but that is probably because the database have not been reorganized in about 5 years and the high use tables have over 100 extents on them.

  2. #2
    Join Date
    Aug 2003
    Location
    Argentina
    Posts
    780
    Hi,

    I think that the value of CLEANERS <= NUMAIOVPS.
    I suggest him that reorganize all the base or the tables with more seven extents.
    Another important theme is the layout of disks, if you use KAIO.
    Please test output onstat -g iof, column "io/s".

    Gustavo

  3. #3
    Join Date
    May 2004
    Location
    New York
    Posts
    248
    Thank you Gustavo, that is exactly what I was thinking.
    The database have not been reorganized in a while, they only have one dbspace spread out across 13 chunks some on the same disk some are not
    and the tables and the extents are all over the place.

    I'm going to monitor iof output for a day, see which chunks are being hit the hardest.

Posting Permissions

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