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  1. #1
    Join Date
    Jul 2002
    Location
    ATL
    Posts
    170

    Unanswered: Backup Very slow

    Hi Folks

    My backup is running very slow.
    Taking one hour for 5G database.
    Iam using adsm for backup.
    It is v7 EE environment with two preocessors and 2G memory.
    Does anybody has any suggestions to make my backup much faster.

    Thanks
    Prasad

  2. #2
    Join Date
    Mar 2003
    Posts
    343
    Have you checked the size of the util heap? Does the backup statement specify the buffer size and the number of buffers used?

  3. #3
    Join Date
    Jul 2002
    Location
    ATL
    Posts
    170
    I cannot use the bufers as iam using TSM for my backup.
    What would be the right backup command if you wanna backup on to TSM.

  4. #4
    Join Date
    Mar 2003
    Posts
    343
    What about the utility heap - can you up that? I am a TSM unaware person, however, if you cannot specify number of buffers and buffer size, then db2 is using the dbm parm backbufsz - can that be upped?

  5. #5
    Join Date
    Aug 2001
    Location
    UK
    Posts
    4,650
    NUMSESSIONS option in the BACKUP Command can be used to open multiple TSM Sessions ...

    Is it only DB2 BAckup that is slow or is it all other backups ... If other backups are also affected, then it could be something outside DB2 (like your Network, TSM Config etc) which causes trouble ...

    HTH

    sathyaram

    Originally posted by cchattoraj
    What about the utility heap - can you up that? I am a TSM unaware person, however, if you cannot specify number of buffers and buffer size, then db2 is using the dbm parm backbufsz - can that be upped?
    Visit the new-look IDUG Website , register to gain access to the excellent content.

  6. #6
    Join Date
    May 2003
    Posts
    369

    some tips- incremental delta backup

    Have you checked the network performance between your DB2 database server and the TSM server? We have slow performance due to network limit. Have you considered implementing TSM LAN Free? This will speed up backup and restore times considerably. Also

    1. increase number of sessions with DB2 and TSM
    2. increase buffers and/or buffer size with TSM
    3. parallelism factor

    ex: db2 backup db mydb online use tsm open 2 sessions with 4 buffers buffer 1024 parallelism 5;

    4. use incremental delta backups

    Example:
    Sunday- full backup
    Monday-Friday- incremental or incremental/delta

    ex: db2 backup db mydb online incremental delta use tsm open 2 sessions with 4 buffers buffer 1024 parallelism 5;

    By using incremental/deltas you can do faster backups during the week. In fact our full backup takes 4-6 hours but deltas only take at most 2 hours. Much quicker to do than a daily full backup.

    -Scott

  7. #7
    Join Date
    Oct 2003
    Posts
    706

    Exclamation

    Also check the physical capacity of your various hardware components. Neither "the number of CPUs" nor "the amount of memory" really helps you at all in this case. What matters very much is: how fast the devices can physically perform their task, and how fast the computer's internal buses (and external wiring) can get the data to them. This is an I/O bound activity, not CPU-bound.

    Many "off the shelf" computers economize on their I/O structure, which is to say they're dog-and-pony slow. Unfortunately, there are a lot of cheap tape-drives out there too. You don't say anything about what kind of hardware you're using. But to give you an example, some computers would only be able to execute a disk I/O operation or a tape I/O operation, but not both, at any one moment in time. Other device configurations would be capable of full parallelism.

    Backup speeds can also, generally speaking, be affected by contention for the database itself. A "great big fat lock" will obviously allow a backup to be more efficient but will lock out other activities wholesale.
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