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  1. #1
    Join Date
    Sep 2002
    Location
    Valencia, California USA
    Posts
    7

    Unanswered: IDS 7.3 DBSPACE vs. Physical Log Size

    I've been reading O'Reilly on this. They have an example where they used
    onspaces to create a dbspace of 100000 KB, and then used onparams
    for a physical log size of 50000 KB.

    I'm curious why the log size is exactly half the size of the dbspace. When looking at the results through onstat -d, the space is then 50% used just
    after initialization.

    Anyone understand this?
    Thanks for any response!

    Coreysan

  2. #2
    Join Date
    Apr 2007
    Location
    Jundiai / SP - Brasil
    Posts
    311

    Cool

    What exactly you don't understand?
    50MB is 50% of 100MB...

    The physical log is allocated in a dbspace... probably is in the dbspace that you looking for on onstat -d..

    look up in onconfig the parameter PHYSDBS...


    sorry my bad English...
    ________________________________________
    César Inacio Martins
    Jundiai / SP - Brasil
    http://www.imartins.com.br/informix - em Português
    http://www.imartins.com.br/informix - English (translated by Google).
    ________________________________________

  3. #3
    Join Date
    Sep 2002
    Location
    Valencia, California USA
    Posts
    7
    thanks for your response. Here's what I don't understand. If I create a dbspace for the DB, the dbspace is actually empty until I load data. Once data is in, then the space is filled up.
    Using that idea, when I create dbspace for physical logging, the dbspace is empty, but when I use onparams, it becomes 50% full before I populate the database with data. If its 50% full, what is it full of?
    The only thing I can figure is that the onparams utility reserves page-space, and that "fills" up the dbspace, so to speak. Is that true or false?

  4. #4
    Join Date
    Apr 2007
    Location
    Jundiai / SP - Brasil
    Posts
    311
    True!

    When you initialize a instance of IDS you need have in your mind 4 thinks: root, logical log, physical log and data...
    - root : space to database SYSMASTER
    - physical log: space reserved to before-images pages....
    - logical log:: space reserved to transactions logs...
    - data: your database...

    By default on the first initialization the configuration put all together, but this is not recommended... at least you need a dbspace for each one.
    some like this:
    rootdbs - only to database sysmaster
    physdbs - only to physical log (allocated with onparams)
    logdbs - only to logical log (allocated with onparams)
    data1dbs - only to your database

    I'm sorry if my English do not help...
    ________________________________________
    César Inacio Martins
    Jundiai / SP - Brasil
    http://www.imartins.com.br/informix - em Português
    http://www.imartins.com.br/informix - English (translated by Google).
    ________________________________________

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