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  1. #1
    Join Date
    Aug 2004
    Posts
    54

    Unanswered: Cache Hit Ration on SAN

    We recently moved a database to the SAN and it is not performing so well. Watching performance logs I have noticed that the Cache hit ratio is only around 60%. I checked memory right away and that seems to be fine. Plenty of physical memory available and only about 40% is committed to use.

    The SAN is currently configured to have 200 mg of Read Cache, I would imagine that is a little low, but not sure.

    This is the first time we have ever put a database on the SAN so our knowledge of optimization is lacking. Any ideas on how to improve performance would be helpful.

    Thanks much

  2. #2
    Join Date
    Jul 2003
    Location
    San Antonio, TX
    Posts
    3,662
    What do you mean "plenty" and what edition of OS and SQL are you running?
    "The data in a record depends on the Key to the record, the Whole Key, and
    nothing but the Key, so help me Codd."

  3. #3
    Join Date
    Aug 2004
    Posts
    54
    By pleanty I mean 650000 K. We are running Windows 2000 and SQL 2000.

    Thanks much.

  4. #4
    Join Date
    Jul 2003
    Location
    San Antonio, TX
    Posts
    3,662
    650MB is plenty? OK then. And I know that you were running some sort of Windows (SQL doesn't run on anything else) with some version of SQL. The question was: "...what edition of OS and SQL?"
    "The data in a record depends on the Key to the record, the Whole Key, and
    nothing but the Key, so help me Codd."

  5. #5
    Join Date
    Feb 2004
    Location
    San Antonio, TX
    Posts
    565

  6. #6
    Join Date
    Feb 2004
    Location
    San Antonio, TX
    Posts
    565
    i screwed up
    get more ram
    Last edited by Ruprect; 12-02-04 at 18:56.

  7. #7
    Join Date
    Aug 2004
    Posts
    54
    I don't think Ram is the problem. We have a totol of 2GB, with 650MB remaining when the server is running slow. Wouldn't remaining RAM drop lower than that if we needed more? If I watch Pages/sec it rarely goes above 1. Watching SQL Memory, the target memory is always equal to the total memory. I think this is a problem with IO on the SAN.

    Thanks much

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