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  1. #1
    Join Date
    Apr 2013
    Posts
    33

    Unanswered: logarchmeth1 off

    we had to turn logarchmeth1 off in a test environment for a different reason (disk full issue). On the other hand, we would like to know the positive impact of turning loggig off.. any improvement in application runtimes ???

    Also, what DB2 performance monitoring variables will show more info specific to application performance with respect to logging (on and off)..

    Mani,
    Jr. DBA

  2. #2
    Join Date
    May 2003
    Location
    USA
    Posts
    5,737
    The main advantage of archive logging is to be able to do online backups, and be able to do rollforward recovery after a backup is restored (rollforward to a specific time or to end of logs), instead of just restoring the backup.
    M. A. Feldman
    IBM Certified DBA on DB2 for Linux, UNIX, and Windows
    IBM Certified DBA on DB2 for z/OS and OS/390

  3. #3
    Join Date
    Apr 2013
    Posts
    33
    Thanks Marcus. I understand the main purpose of logarchmeth1 and logarchmeth2. Since DB2 doesn't have to do additional workload of logging every update or insert or delete LRSN info, would that account for any savings in CPU or I/O or logging..etc..

  4. #4
    Join Date
    May 2003
    Location
    USA
    Posts
    5,737
    DB2 does the same amount of logging with circular logging (compared to archive logging), which is necessary for crash recovery. For example, if the system crashes, there may be committed data in bufferpools not written to tablespaces on disk, and sometimes there could be uncommitted data that has been written to tablespaces on disk. So all database changes must be logged for DB2 to correctly recover in case of a crash, even with circular logging. There might be some very minor differences in logged data between circular and archive logs, but not enough to affect performance. But make sure you have enough primary and secondary log files allocated, and that they are appropriate size.
    Last edited by Marcus_A; 04-16-13 at 17:43.
    M. A. Feldman
    IBM Certified DBA on DB2 for Linux, UNIX, and Windows
    IBM Certified DBA on DB2 for z/OS and OS/390

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