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Thread: RMAN backup output file growth

  1. #1
    Join Date
    Sep 2001
    Posts
    13
    We use RMAN to backup to disk. We do not use the recovery catalog. We only keep 1 last night's backup on disk. We use the

    backup format.... (database);

    then we do the alter system archive log current and the backup command on them. 2 weeks ago the db file that the backup (database) yielded was 34.3 gb. We had our data separated into 4 tablespaces.

    Then, we did an upgrade. We made a 5th tablespace and moved a large (10 gb data/index) to the new tablespace and we moved a few others around as well. Now the RMAN backup puts out a file that is 51.5 gb.

    I have been researching & researching (I'm a novice). I have found that RMAN is only supposed to backup data blocks that have been used. My thoughts are that RMAN is backing up all the empty spots where the files were. I keep seeing a command 'change archivelog all validate'. I would like it to 'forget' that those spots were once used.

    But, I don't know how to prove this or fix this or whatever. We are at the point where we will not restore back to before the upgrade.

    Any ideas?
    Thanks in advance.

  2. #2
    Join Date
    Oct 2000
    Location
    Germany
    Posts
    1,185
    Two ideas.

    If your blocks are not full, then you have no choice but to back up empty space. Maybe you can reorg the database. You can export and then import, but read some documentation first to make sure your parameters are appropriate.

    Another fix is to use the filesperset command so that there are many RMAN files. You could zip the files with a script and compress them and save space that way.

    Good luck.
    David Knight
    OCP DBA 8i, 9i, 10g

  3. #3
    Join Date
    Oct 2000
    Location
    Saskatoon, SK, Canada
    Posts
    3,925
    What kind of backups are you doing.

    FULL / LEVEL 0. I would try LEVEL 0.

    Refer: http://www.oradoc.com/ora817/server....onc.htm#436086


    Sam
    Thanx
    Sam



    Life is a journey, not a destination!


  4. #4
    Join Date
    Jun 2001
    Location
    Helsinki. Finland
    Posts
    3,938
    Have in mind that full backups saves all blocks in datafile, while level-0 incremental saves only those blocks that have data in them.


  5. #5
    Join Date
    Sep 2001
    Posts
    13
    We do the exact same backup every night as we have done for years. I have not changed it. I have been tracking the size for several months. It normally grows about 100mb per week. It jumped from 34 gig to over 51 gig in one day.

    Here is the command, ran with a nocatalog & cmdfile:

    run {
    allocate channel d1 type disk;
    backup
    format "/oraback/db_back%s_$DATE"
    (database);
    sql 'alter system archive log current''
    backup
    fileperset 1
    format "/oraback/arch_back%s_$DATE"
    (archivelog all delete input);
    }

    Since I have been here, the backup command has not specified any incremental command.

    What would cause the database backup file see such a growth from one day to the next?

    Thanks again,
    DJ

  6. #6
    Join Date
    Oct 2000
    Location
    Saskatoon, SK, Canada
    Posts
    3,925
    You seems to do a full database backup. So it would make sense, that the backup is copying all your db block, i.e used and unused. The reason you would have been seeing the growth is because as you mentioned, you have moved some tablespaces around. That would be contributing to your growth. Do a level 0 then it would all be fine.

    Sam
    Thanx
    Sam



    Life is a journey, not a destination!


  7. #7
    Join Date
    Jun 2001
    Location
    Helsinki. Finland
    Posts
    3,938
    I would suggest you start using a Recovery Catalog (besides switching from Full to Level 0).


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