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  1. #1
    Join Date
    Mar 2006
    Location
    Tuticorin, India
    Posts
    103

    Unanswered: Tablespace Backup Size

    Env: DB2 8.2/AIX 5.3

    A DMS tablespace size is 150 GB but only 1 GB is used. HWM and Pages used remains the same.

    If a backup is taken, will it backup all 150 GB of tablespace or only 1 GB of the used space( or HWM whichever is high) ?

  2. #2
    Join Date
    May 2003
    Location
    USA
    Posts
    5,737
    It will not backup all 150 GB that is allocated if HWM is 1 GB. But you should use the compression option on the backup command anyway. However, I am not sure if the backup will have to read the entire allocated space to find out if there are any pages to backup.
    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
    Mar 2006
    Location
    Tuticorin, India
    Posts
    103
    Thanks.

    I did a quick test and it backs up only 1 GB. I increased the HWM level of tablespace and noticed that backup size/time increase proporionately.

    I think the backup uses the HWM to find out how many pages to backup instead of reading all allocated space.

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