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  1. #1
    Join Date
    Jan 2003
    Posts
    1,605

    Unanswered: Backup consumes too much CPU power - how to reduce CPU consumption

    Hi,
    using DB2 ESE v9.5 FP2 on Linux. At the time on-line backup is executed computer resources are eaten up too much, especially CPU is way too much consumed, so users using DB2 database are complaining that applications freezes and then unfreezes after few minutes after backup is finished.

    Now backup command is:
    db2 backup db mydb online to /mydir include logs

    I have read through documentation that there is some kind of parameter that computer resources are not eaten up to 100% during backup process. Using backup command there is "UTIL_IMPACT_PRIORITY priority" option and settings this parameter using backup command it suggest to also set util_impact_lim dbm cfg parameter. As I see this parameter is set to 10% in our system (default). What I am wondering now is what has the util_impact_priority priority settings effect? If I set it to 10% is this 10% of 10% or what?

    I have also tested this util_impact_priority priority settings to 10% and util_impact_lim also to 10% and I have monitored cpu consumption by using Linux top command and as I see more then 10% (20% or more) is consumed.

    How should I set this two parameters that cpu consumption will not exceed 10% cpu consumption?

    Regards,
    Grofaty

  2. #2
    Join Date
    May 2003
    Location
    USA
    Posts
    5,737
    I just use the one on the backup command itself. I don't believe it limits only CPU, so if you set it to 10, then CPU could go over 10%. But I doubt you will have problems if you do that.
    M. A. Feldman
    IBM Certified DBA on DB2 for Linux, UNIX, and Windows
    IBM Certified DBA on DB2 for z/OS and OS/390

  3. #3
    Join Date
    Jan 2003
    Posts
    1,605
    Quote Originally Posted by Marcus_A
    I just use the one on the backup command itself.
    Sorry, I don't quite understand...

    Do you mean?
    db2 backup db mydb online to /mydir UTIL_IMPACT_PRIORITY include logs
    or
    db2 backup db mydb online to /mydir UTIL_IMPACT_PRIORITY 10 include logs

    I have tested above commands and also backup without UTIL_IMPACT_PRIORITY parameter and I don't really see any change in CPU consumption. UTIL_IMPACT_LIM dbm cfg is set to 10. I used top command to see what is happening with CPU during backup process. It looks like util_impact_priority does not have any effect. Strange. Any idea why?
    Last edited by grofaty; 03-17-09 at 05:10.

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