Parameter Wednesday: DB CFG UTIL_HEAP_SZ

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7 Responses

  1. harish pathangay says:

    consider restore utility is overwriting an existing db, then i can update db cfg of existing db before starting restore utility there by getting increased performance.

    how will you use this parameter(util heap) if restore is creating new database?
    will restore utility refer db cfg inside the backup image during restore process?
    thanks.

    • Ember Crooks says:

      You can always create a database and set the configuration before restoring into it. Restore will use the cfg of the database it is restoring into, if there is one. If restoring to a new database, it will use what is in the backup image.

      • harish pathangay says:

        Hi,
        Thanks for your inputs and suggestions.

        Question in General with Restore Utility:
        Will Restore Utility use the DB CFG parameters stored inside the backup image file during Restore process or will it apply the DB CFG after restoring complete at the end phase?

        My Observation as a test case:
        Test Case 1:
        create data base db1, update db cfg with num_ioserver set to 6, activate and deactivate db
        backup data base
        drop data base
        restore database db1 – utilizes 255 pre-fetchers during restore process and crashes the instance. (db2pd -edus reveals db2pfchr threads)
        terminate all process,do instance restart.

        create db1 update db cfg with num_ioservers 6
        restore database db1 from backup image – utilizes only 6 pre-fetchers.(db2pd -edus reveals db2pfchr threads)

        my observation from test case:
        when restore process is creating a new database – it is not referring the DB CFG inside the backup image.
        when restore process is overwriting an existing database – it is using the correct num_ioserver configuration, because the db is active with cfg parameters applied.

        if restore utility creates database it is not referring DB CFG upfront,it is applying the DB cfg parameters after doing the restore process at the end phase?

        Win 7,DB2 Express C 10.5,32 bit,1GB RAM,Intel Dual Core CPU 1.6GHz

        Let me know your inputs.

        Thanks,
        Harish Pathangay

        • Ember Crooks says:

          I don’t know when the db cfg is applied. From your tests, it appears to be at the end of the restore.

  2. Abdul Qader says:

    Hi Ember,

    Noticed that if the backup utility is an online backup then 50% of UTIL_HEAP_SZ is used, where as when the backup is an offline backup then the amount of UTIL_HEAP_SZ is 90%.

    ONLINE BACKUP – 50% of UTIL_HEAP_SZ
    OFFLINE BACKUP – 90% of UTIL_HEAP_SZ

    • Ember Crooks says:

      Interesting. It is supposed to be all of it for an offline backup, because all utilities are incompatible with offline backup.

  1. September 22, 2015

    […] be aware of the usage of the utility heap by other utilities – LOAD, REDISTRIBUTE, etc. See my entry on the utility heap for more […]

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