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  1. #1
    Join Date
    Jul 2009
    Location
    USA
    Posts
    53

    Unanswered: HADR - logs transfer?

    Does HADR copy the logs from primary to standby or does it transfer the log records using some memory area and then recreates them on standby? What happens to the logs on standby after they've been applied?

  2. #2
    Join Date
    Jun 2009
    Posts
    272
    Log pages are transferred through network from the primary and are first written to the logbuffer on the standby and then written to the log file.

  3. #3
    Join Date
    May 2003
    Location
    USA
    Posts
    5,737
    To add to the above remark:

    If you use HADR Nearsynch mode, then the transaction will be considered as committed (assuming a commit is issued or auto-commit) on the primary when the log record is transferred to the HADR log buffer on the standby.

    If using HADR Synch mode, the transaction will be considered as committed (assuming a commit is issued or auto-commit) on the primary only when the log record is written from the HADR buffer on the standby to the log file on disk on the standby.
    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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