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  1. #1
    Join Date
    Jan 2009
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    Unanswered: db2/tsm best restore times

    In a couple of hours I am going in a meeting to advice how to optimize restore times in case of an emergency. We are working with TSM and this is configured that everything is going to tape instantly (db2v97 on aix).
    Normally we have a weekly online backup and transaction logs (business as usual). I could advice to extend the backup housekeeping logic with daily delta or incremental backups or .... I was thinking:

    When I increase the size of the logfiles considerably and decrease the number of active logfiles I would have less and bigger trx-logfiles. So in case of a restore/rollback TSM would have fewer tape-mounts and this would speed-up the process.

    Is this a sane thought? Am I taking risks or overlooking something? Somebody already experimented with such settings?
    Somewhere between " too small" and " too large" lies the size that is just right.
    - Scott Hayes

  2. #2
    Join Date
    Apr 2006
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    Belgium
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    Provided Answers: 11
    if bigger logfiles - the logarchive interval would become larger -
    in case of crash and logfile corrupted - less to recover ....
    retrieve time from tsm longer..
    I monitor archive interval - and try to reduce the size - so in average, normal working hours, we have an archive each 0,5 hour. so in case of crash (disk - logfile not yet archived) we loose max 0,5 hrs
    Best Regards, Guy Przytula
    Database Software Consultant
    Good DBAs are not formed in a week or a month. They are created little by little, day by day. Protracted and patient effort is needed to develop good DBAs.
    Spoon feeding : To treat (another) in a way that discourages independent thought or action, as by overindulgence.
    DB2 UDB LUW Certified V7-V8-V9-V9.7-V10.1-V10.5 DB Admin - Advanced DBA -Dprop..
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  3. #3
    Join Date
    Jan 2009
    Location
    Zoetermeer, Holland
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    Thanks Guy.
    You are right: when your active log file gets damaged you loose more. Cannot I reduce that risk by doubling the active logs by means of a mirror log path. (1st log to SAN and mirror to local disk)? When your SAN explodes you still got your mirror & your TSM archives.
    How do you think about my theory to reduce the number of TSM-tape mounts?
    Somewhere between " too small" and " too large" lies the size that is just right.
    - Scott Hayes

  4. #4
    Join Date
    Apr 2006
    Location
    Belgium
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    Provided Answers: 11
    all depends : how much do you archive (logfiles) ?
    how long do you keep backup-log files ?
    do you use cleanup script for older backups/logs
    many questions/answers depending of how critical is the db
    how much time can you effort to recover
    how much to loose is tolerated...
    can you restart data from certain pit in case of loss
    we archive to disk (faster-no wait for tape) and use migrate storage pool to tape (asynchronous )
    Best Regards, Guy Przytula
    Database Software Consultant
    Good DBAs are not formed in a week or a month. They are created little by little, day by day. Protracted and patient effort is needed to develop good DBAs.
    Spoon feeding : To treat (another) in a way that discourages independent thought or action, as by overindulgence.
    DB2 UDB LUW Certified V7-V8-V9-V9.7-V10.1-V10.5 DB Admin - Advanced DBA -Dprop..
    Information Server Datastage Certified
    http://www.infocura.be

  5. #5
    Join Date
    Jan 2009
    Location
    Zoetermeer, Holland
    Posts
    746
    my client is a bank: no loss tolerated. They just want to know if recovery can be speed-ed up. Archive to disk would by my choice as well, but TSM/disk is a fact-of-life which I cannot change. The only thing I can change is housekeeping schedules and db cfg parameters.
    Somewhere between " too small" and " too large" lies the size that is just right.
    - Scott Hayes

  6. #6
    Join Date
    Aug 2008
    Location
    Toronto, Canada
    Posts
    2,367
    Quote Originally Posted by dr_te_z View Post
    We are working with TSM and this is configured that everything is going to tape instantly
    Why is it going to tape? We send backups/logs for confidential data directly to TSM tape and I find it's taking a lot longer (mainly due to time spent waiting for available tape).

  7. #7
    Join Date
    Jan 2009
    Location
    Zoetermeer, Holland
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    746
    Quote Originally Posted by db2girl View Post
    Why is it going to tape? We send backups/logs for confidential data directly to TSM tape and I find it's taking a lot longer (mainly due to time spent waiting for available tape).
    True. Company policy, not open for discussion. Gotto deal with it.
    Somewhere between " too small" and " too large" lies the size that is just right.
    - Scott Hayes

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