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  1. #1
    Join Date
    Sep 2004
    Posts
    24

    Unanswered: HADR an failover

    hi,
    maybe someone can bring light in the dark.
    i have two virtuell maschines with DB2 9.5 and HADR running.

    VM1 is primary, VM2 is standby.

    i want to test the takeover in case of an error of VM1
    and disabled the network adapter of VM1.

    i thought VM2 would become primary but the DB2 got the status: remote catch-up !?!

    does the failover not switch the db2 rolles automaticaly?

    thanks for advice
    anwy

  2. #2
    Join Date
    Apr 2008
    Posts
    39
    No, the failover does not switch roles automatically. We need to manually perform takeover operation.

    We can perform HADR takeover operation using one of the following ways.

    1) Switch database roles: primary becomes standby,standby becomes primary
    2) Failover from primary to standby: primary does not switch to standby.

    switch database roles can be done on standby database as follows
    TAKEOVER HADR ON DB <database name>


    Failover from primary to standby: can be done as follows
    TAKEOVER HADR ON DB <database name> by FORCE

    Note that the standby database should be in peer state else the failover does not happen.

    Thanks,
    Madhavi

  3. #3
    Join Date
    May 2003
    Location
    USA
    Posts
    5,737
    Quote Originally Posted by anwyuta
    hi,
    maybe someone can bring light in the dark.
    i have two virtuell maschines with DB2 9.5 and HADR running.

    VM1 is primary, VM2 is standby.

    i want to test the takeover in case of an error of VM1
    and disabled the network adapter of VM1.

    i thought VM2 would become primary but the DB2 got the status: remote catch-up !?!

    does the failover not switch the db2 rolles automaticaly?

    thanks for advice
    anwy
    HADR keeps the databases in synch and does a takeover when instructed by a DBA or some automated process. There are cluster managers that will detect a failure of a server and issue the HADR takeover command.

    HADR comes with a free copy (for 2 nodes) of the Tivoli System Automation cluster manager, if you want to use that one, but there are other cluster managers that also work.
    M. A. Feldman
    IBM Certified DBA on DB2 for Linux, UNIX, and Windows
    IBM Certified DBA on DB2 for z/OS and OS/390

  4. #4
    Join Date
    Sep 2004
    Posts
    24
    Markus,

    can you please tell me more about the fact that
    HADR comes with a free copy (for 2 nodes) of the Tivoli System Automation cluster manager?

    where can ich find it? we have a licence of the DB2 Datawarehouse Enterprise Edition 9.5.

    maybe you can recommend other cluster manager?

    thanks in advance
    anwyuta

  5. #5
    Join Date
    Jun 2003
    Posts
    127
    The only way you can automate is to come up with a script (probably Perl would be a good option) to ping the nodes. You have to make sure that they are in peer state and needs extensive testing. At my old job, it was a shell script we used but Perl would be better.
    Also TSA (Tivoli System Automation) would be an option.

  6. #6
    Join Date
    May 2003
    Location
    USA
    Posts
    5,737
    Quote Originally Posted by anwyuta
    Markus,

    can you please tell me more about the fact that
    HADR comes with a free copy (for 2 nodes) of the Tivoli System Automation cluster manager?

    where can ich find it? we have a licence of the DB2 Datawarehouse Enterprise Edition 9.5.

    maybe you can recommend other cluster manager?

    thanks in advance
    anwyuta
    HADR does not work with Data Partitioning (DPF) so I don’t know if it is included with DB2 Datawarehouse Enterprise Edition 9.5. But if you have Passport Advantage or the Licensed Media discs, then you should be able to find it. Some parts of TSA are actually installed by default as part of the DB2 install unless you request that it not be installed.

    I tried to use TSA about 3 years ago when it was first included with 8.2 ESE and it had some problems. There have been some improvements and it may work better now, but it is still fairly complex IMO. My shop uses Red Hat Cluster Manager. These decisions are usually made by the System Administrators, especially if they have been using a Cluster Manager for other systems (non DB2) previously, and are already familiar with how it operates.

    I have heard that Veritas Cluster Manager also works well with HADR (requires Veritas HADR agent add-on).
    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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