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  1. #1
    Join Date
    Mar 2010
    Posts
    6

    Red face Unanswered: Steps to split a primary database to use it as standby database

    Hi,

    I am quite new to DB2 world.

    I need to split a primary database to use it as standby database.

    I am aware of the following steps:
    1) Suspend I/O on the primary database
    2) Use appropriate operating system-level commands to split the mirror or mirrors from the primary database
    3) Resume I/O on the primary database
    4) Catalog the mirrored database on the secondary system
    5) Start the database instance on the secondary system
    6) Initialize the mirrored database on the secondary system using db2inidb
    7) etc etc

    Problem is I am not aware of executing the step number: 2

    I am using OS as SuSE 10u2. I am not using any external memory device
    I have 2 different machine of SuSE 10u2 and need to configura 1 as Primary database and second as Standby database.

    Can you please help me with proper steps to execute and create split mirror of the database and import it as standby database on another machine ?

    Please correct me if I am wrong anywhere.

  2. #2
    Join Date
    Jan 2003
    Posts
    4,292
    Provided Answers: 5
    What DB2 version are you using?

    What is your intention for the standby system?

    Andy

  3. #3
    Join Date
    Jun 2003
    Location
    Toronto, Canada
    Posts
    5,516
    Provided Answers: 1
    "Split mirror" operation must be supported by your storage subsystem. Talk to your storage administrator. If I were you I'd choose the backup method of setting up HADR.
    ---
    "It does not work" is not a valid problem statement.

  4. #4
    Join Date
    Mar 2010
    Posts
    6
    Quote Originally Posted by ARWinner View Post
    What DB2 version are you using?

    What is your intention for the standby system?

    Andy
    I am using Db2 version 9.7

    My objective for creation of standby database is to configure High Availability mode between the two DB2 servers.

  5. #5
    Join Date
    Mar 2010
    Posts
    6
    Quote Originally Posted by n_i View Post
    "Split mirror" operation must be supported by your storage subsystem. Talk to your storage administrator. If I were you I'd choose the backup method of setting up HADR.
    I am not using any special storage subsystem. I just need to copy split Db on another machine or shared location.

  6. #6
    Join Date
    May 2003
    Location
    USA
    Posts
    5,737
    Quote Originally Posted by amit_nsharma View Post
    I am not using any special storage subsystem. I just need to copy split Db on another machine or shared location.
    I have done what you want to do using a Hitachi SAN subsystem which specifically has support for the doing a split mirror, and they supplied the commands to do the split. As mentioned above, this has to be supported by your storage vendor to the best of my knowledge. If there is some kind of generic support at the OS level, I am not aware of it, unless you could do something with RAID 10 and split volumes that way.

    Starting with DB2 9.7 FP1 there is support for read only access on the HADR standby with isolation level UR. However, you will have to fully license the standby server in that case, instead of the 100 PVU charge if the HADR standby does not have read access activated.
    M. A. Feldman
    IBM Certified DBA on DB2 for Linux, UNIX, and Windows
    IBM Certified DBA on DB2 for z/OS and OS/390

  7. #7
    Join Date
    Jan 2003
    Posts
    4,292
    Provided Answers: 5
    This is what happens in a split mirror:

    1) Suspend Writes on the database server - This means that no writes to disk are allowed. All applications wanting to write data will wait until the write suspend is canceled
    2) The entire database files are copied to the target system. How long this takes depends on the disk system
    3) Write suspend is canceled. Users can write data again.


    The problem is step 2. It needs to happen real fast (< 1 second is optimal). If it does not happen quickly then you have users calling you at all hours because the system is not working in their eyes. That is why there is special hardware/software to perform this task. Without the special hardware, the only way to copy the entire database to the target is with an OS copy command. This will be very slow as the target is a remote system. Most shops cannot afford for the system to periodically "hang" for long periods of time.

    Since you are using conventional hardware, you need to look elsewhere for you HADR needs.

    Andy

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