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  1. #1
    Join Date
    Nov 2007
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    Sydney, Australia
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    Unanswered: create tempdb in swap space

    Hi,

    I have to install sybase on AIX tommrow. I am a novice when it comes to sybase and have never done it before. I have been asked to create tempdb on a swap device created for it for performance reason.]

    My question is does the installation ask you that on which device you want t configure temdb? In this case I can enter the swap device? and if not then what are the steps involved in creating tempdb on swap device? Do I have to do it after the installation as a seperate process?

    Please help

    Thanks,

    Atap

  2. #2
    Join Date
    May 2005
    Location
    South Africa
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    1,365
    Provided Answers: 1
    No, a small tempdb is created on the master device during install
    Do it as a separate process by adding a tempdb device afterwords

  3. #3
    Join Date
    Sep 2003
    Location
    Switzerland
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    443
    Theres a known performance gain if you create the first portion after master in /tmp and the rest in a different filesystem. Also dsync should be off for tempdb devices.

    i.e.

    If you want a 1g tempdb.

    a) 2MB in master (default).
    b) 100MB in /tmp
    c) 900MB in /mytempdbfs


    for b) make sure you touch the file in RUN_SERVER file as /tmp gets whacked out in case of a OS reboot.

  4. #4
    Join Date
    Nov 2007
    Location
    Sydney, Australia
    Posts
    13
    Thanks guys,

    Please correct me if my process is incorrect

    1. From installation create tempdb on the default master device which is /sybase/system
    2. Extend tempdb by creating 2 2G devices in /sybase/tempdb
    3. Extend tempd by running the alter database commands by allocating space on the two devices
    4. drop the device for tempdb in master called /systenm/tempdb

    So at the end of this I have my tempdb configured in swap space.

    Thanks

  5. #5
    Join Date
    Sep 2003
    Location
    Switzerland
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    443
    tats not what I said. Knowingly or unknowingly you asked the right question. /tmp is totally different from user created filesystems. Please read about /tmp and my post and then post again if u have any questions.

  6. #6
    Join Date
    Nov 2007
    Location
    Sydney, Australia
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    13
    Thanks trvishi,

    I just read about tempdb in the performance and tuning guide. I will follow the steps to delete the segments related to tempdb in the master device. I will have to expand tempdb on the ram disk. What do I need to specify in the run startup file so that if the server reboots then the device is created again.

    Please advise.

    Regards,

    Atap

  7. #7
    Join Date
    May 2005
    Location
    South Africa
    Posts
    1,365
    Provided Answers: 1
    Quote Originally Posted by atapojha
    What do I need to specify in the run startup file so that if the server reboots then the device is created again
    Quote Originally Posted by trvishi
    for b) make sure you touch the file in RUN_SERVER file
    e.g.
    touch /tmp/tempdbdev.dat

  8. #8
    Join Date
    Sep 2003
    Location
    Switzerland
    Posts
    443
    Quote Originally Posted by atapojha
    Thanks trvishi,

    I just read about tempdb in the performance and tuning guide. I will follow the steps to delete the segments related to tempdb in the master device. I will have to expand tempdb on the ram disk. What do I need to specify in the run startup file so that if the server reboots then the device is created again.

    Please advise.

    Regards,

    Atap
    Also dont drop the segments in the master (The 2MB one created while the server is built). Because, if you had to recover the server without any tempdb devices, the server wont come up.

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