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  1. #1
    Join Date
    Apr 2004
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    79

    Unanswered: Reduce backup time

    Hi,

    I am using ASE 12.5 on Windows 2000.

    I am looking to make database dumps faster. At the moment,we are using default value of shared memory (48MB) for backup server. My backup command looks like:

    dump database dbane to 'compress::8::f:\dump\dbane.dat'

    Will it help in my case if I increase shared memory for backup server (for dump as well as load).

    Please help.


    EDIT: Just observed that loading a compressed dump takes less time than loading a normal dump...I am bit surprised with this..

    Regards
    Last edited by Wilson77; 09-26-06 at 06:49.

  2. #2
    Join Date
    Jan 2003
    Location
    Geneva, Switzerland
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    353
    Using a level 8 compression uses a lot of CPU for a fairly small improvement in size. I'd use the default compression level instead.

    Michael

  3. #3
    Join Date
    Apr 2004
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    79
    Using level 8 compression, I am able to reduce dump filesize to 20% which is quite significant.

    Any comments on shared memory....

  4. #4
    Join Date
    Jan 2003
    Location
    Geneva, Switzerland
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    Quote Originally Posted by Wilson77
    Using level 8 compression, I am able to reduce dump filesize to 20% which is quite significant.
    Sure. But the amount of CPU needed to achieve the additional compression compared to a level 5 compression is significant, and the difference in actual compression is usually not that great - hence my comment that reducing the compression level usually improves the speed (unless you have very fast CPUs...)

    Michael

  5. #5
    Join Date
    Apr 2004
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    79
    True, I checked with level 5 compression and there was not much difference betwn level 5 and level 8 from filesize per se.

    Thing is that I have a new server with lots of CPU power and a lot of available memory...

  6. #6
    Join Date
    Sep 2003
    Location
    Switzerland
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    443
    1) Try striping.
    2) You can play around with the -m option in the RUN file.

  7. #7
    Join Date
    Aug 2002
    Location
    Madrid, Spain
    Posts
    97
    Quote Originally Posted by Wilson77
    True, I checked with level 5 compression and there was not much difference betwn level 5 and level 8 from filesize per se.

    Thing is that I have a new server with lots of CPU power and a lot of available memory...
    Try also with compression level 2. We changed from level 4 to 2 in Unix and reduced time by 20 % with a small increase in dump size (below 10%). Level 1 is quite similar to 2.

    Consider what you pretend by compressing dumps. From no compression to the smallest compression there's an enormous reduction in dump size at a noticeable cost in duration and CPU. It's worth the cost. But higher compression levels only add small disk gains at a cost which may be very high.

    As trvishi said, another common solution is to use several stripes. They should be in different disks; else, contentions may eliminate the possible benefits.

    Regards,
    Mariano

  8. #8
    Join Date
    Apr 2004
    Posts
    79
    Quote Originally Posted by corral
    Try also with compression level 2. We changed from level 4 to 2 in Unix and reduced time by 20 % with a small increase in dump size (below 10%). Level 1 is quite similar to 2.

    Consider what you pretend by compressing dumps. From no compression to the smallest compression there's an enormous reduction in dump size at a noticeable cost in duration and CPU. It's worth the cost. But higher compression levels only add small disk gains at a cost which may be very high.

    As trvishi said, another common solution is to use several stripes. They should be in different disks; else, contentions may eliminate the possible benefits.

    Regards,
    Mariano
    Thanks for your post..with Level 2, I am able to reduce the time as well as filesize to a considerable level.

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