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Thread: Hadr

  1. #1
    Join Date
    Sep 2009
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    66

    Unanswered: Hadr

    2 Questions:

    1. What happens if primary and standby servers get rebooted without stopping HADR? Will HADR reconnect by itself after reboot?

    2. What happens if HADR_TIMEOUT and HADR_SYNCMODE are not set to the same value on both primary and standby?

  2. #2
    Join Date
    May 2003
    Location
    USA
    Posts
    5,737
    1. You will have to activate the databases, and then they will usually synch up (HADR peer state).
    2. Don't know, because I am not stupid enough to try it.
    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
    Jul 2013
    Location
    Moscow, Russia
    Posts
    666
    Provided Answers: 55
    Quote Originally Posted by L_DBA_L View Post
    2. What happens if HADR_TIMEOUT and HADR_SYNCMODE are not set to the same value on both primary and standby?
    HADR_TIMEOUT must be the same on all databases, otherwise you get ADM12513E rc: 7

    HADR_SYNCMODE can be different only if you use at least DB2 10.1 and the HADR_TARGET_LIST parameter is used. In this case the actual synchronization mode is one that you set on primary.
    It's hard to find a reason to do this with 2 databases only (when your standby is less powerful?), but you might use different sync modes for principal and auxiliary standby.
    For example, your principal is local to primary and auxiliary is remote. You might set HADR_SYNCMODE to NEARSYNC on primary and principal (local) standby and (SUPER)ASYNC on auxiliary (remote). So, when you decide to promote your auxiliary to primary for some reason, your applications will wait less (or will not wait at all) for acknowledgement from the remote principal standby.
    Regards,
    Mark.

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