Resetting the log RBA value in a data sharing environment Start of change(6-byte format)End of change

Before the member of a data sharing group reaches the end of the log RBA range, you must reset the log RBA value for that member.

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Before you begin

Db2 11 introduces extended 10-byte RBA and LRSN formats.

The recommended response before your Db2 data sharing group reaches the end of the 6-byte log RBA range is to convert page sets to use the 10-byte format. For details see What to do before RBA or LRSN limits are reached and The extended 10-byte RBA and LRSN in Db2 12.

However, you can continue to use the following procedure in Db2 12 until you complete the conversion.

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Procedure

To reset the log RBA value in a data sharing environment:

  1. Issue the STOP DB2 command to quiesce the member that is approaching the end of the log RBA range.
  2. Restart this member in ACCESS(MAINT) mode.
  3. Issue the -DISPLAY THREAD command. Ensure that there are no INDOUBT or POSTPONED ABORT units of recovery.
  4. Issue the -DISPLAY DATABASE(*) SPACENAM(*) RESTRICT command. Ensure that all restricted states are removed.
  5. Quiesce the member again by issuing the -STOP DB2 command.
  6. Optional: Start a new member to take over the work of the member that is quiesced. If using another member is an acceptable solution, you can leave the original member stopped indefinitely.
  7. Optional: Before you cold start the member, complete this step to avoid a potential performance issue that is caused by log formatting.
    When the residual RBA range is greater than the log truncation point, Db2 resets the high used RBA (HURBA) for the active logs after the cold start of a member. This action avoids log read errors that can result from reading residual log data with higher RBA values from peer members of the data sharing group. The first time the logs become current, Db2 must format the active logs ahead of the log writes until the log is full.

    To preformat the active logs before a cold start:

    1. Delete and redefine the active logs with IDCAMS.
    2. Format the empty logs by using the DSNJLOGF utility.
    3. Use the DSNJU003 utility to delete the active logs from the BSDS and add the logs back in with no RBA range. Adding the logs back in with no RBA range shows that the logs are empty.
    During the subsequent cold start, Db2 detects these changes to the active logs and does not reset the HURBA. Therefore, log formatting is not required ahead of the log writes.
  8. To bring the original member back into the data sharing group, you must cold start the member with a STARTRBA of 0 (zero). To cold start the member:
    1. Make a full image copy of all data by using the COPY utility.
      For example, in a data sharing group with two members, where you are resetting the log RBA of the first member, make a full image copy by using the second member. The first member must remain quiesced for awhile. The length of time that the member is quiesced depends on how long it takes to establish a new recovery base and the time required for the logs from the quiesced member to no longer be required for any form of recovery. After you are satisfied that the logs are not required for recovery purposes, you can reset the log RBA for the quiesced member and restart the member.
    2. Start of change Stop all IFI applications that might issue READS calls for IFCID 0306 to read log records from the member that you are cold starting. End of change
    3. Cold start the first member back to the RBA value of 0 (zero).
      This step removes all log data from the BSDS, and you can use the member again. This step requires utility DSNJU003 with the following options: 
      CRESTART CREATE,STARTRBA=0,ENDRBA=0
    4. Start of change Restart all IFI applications that you stopped in step 8.b. End of change