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Thread: Database size

  1. #1
    Join Date
    Apr 2004
    Posts
    1

    Unanswered: Database size

    Hi,

    I am new with Informix and I am very worry with my DB spaces. The informix data base was installed under the /home file system that was with 74% of used space, suddelly the file system grown to 97%.
    1 - What is going on?
    2 - How can I release space?

    Thanks for any help

    Nilzelio

  2. #2
    Join Date
    Mar 2004
    Location
    Netherlands
    Posts
    183
    When you define dbspaces Informix is claiming the maximum needed space (the size you specified) from the OS. It will never grow automatically. You can drop a single chunk with:
    onspaces -d <dbspace> -p <path+filename> -o <offset in kb>

    The firts chunk of a dbspace can only be dropped by dropping the dbspace itself. This can be done with:
    onspaces -d <dbspace>

    Chunks and spaces can only be dropped when they are empty (sbspaces however can be dropped when they are used, but you have to specify the -f flag)

    Hope this helps,

    Rob Prop

  3. #3
    Join Date
    Sep 2003
    Location
    Third rock from the sun
    Posts
    15
    Originally posted by RobP
    When you define dbspaces Informix is claiming the maximum needed space (the size you specified) from the OS. It will never grow automatically. You can drop a single chunk with:
    onspaces -d <dbspace> -p <path+filename> -o <offset in kb>

    The firts chunk of a dbspace can only be dropped by dropping the dbspace itself. This can be done with:
    onspaces -d <dbspace>

    Chunks and spaces can only be dropped when they are empty (sbspaces however can be dropped when they are used, but you have to specify the -f flag)

    Hope this helps,

    Rob Prop

    But it is recommended that you drop a chunk one by one... then the last one would be the dbspace itself..

    However.. if your database is very big, then it is recommended that you use SAN storage. Then you can use raw device to create the dbspace and add the chunks..

  4. #4
    Join Date
    Oct 2003
    Posts
    706

    Thumbs up

    There's a reason why (big, multi-user) DBMSes commonly request filespace in chunks, and why they immediately allocate all of it and do not release it. The reason is that "extending a file's size" is typically a fairly expensive operation. But muddling about in the space that you own is cheap. And this "muddling" is being done by optimized, application-specific algorithms within the DBMS.

    PC-oriented databases commonly allocate space on-demand, then once again they never release it back to the OS.

    Both of these strategies have sound reasoning behind them, and the DBMS should generally be left to its own decisions.
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