DSNB319A csect-name THERE IS A SHORTAGE OF SPACE IN GROUP BUFFER POOL gbp-name

Explanation

The amount of storage in the group buffer pool (GBP) coupling facility structure available for writing new pages is low. The GBP is 75 percent full with changed data. As the GBP fills with changed data, the castout thresholds are continuously reached, and the castout engines must continuously work to attempt to keep the number of changed pages in the GBP below the castout thresholds. Also, the more changed data the GBP contains, the less efficiently it operates. Completely running out of GBP storage can result in transaction delays and in pages being added to the logical page list (LPL).

System action

Db2 processing continues.

This message is non-scrollable. It remains highlighted on the console until you take the appropriate action.

This message might not be automatically deleted in a pre SP5.2.1-JES3 environment.

Operator response

Contact the system programmer to fix the storage problem.

System programmer response

You can relieve the GBP storage shortage by taking one or more of the following actions:
  • Use the ALTER GROUPBUFFERPOOL command to lower the CLASST and GBPOOLT castout thresholds.
  • Use the ALTER GROUPBUFFERPOOL command to lower the GBPCHKPT GBP checkpoint frequency.
  • Use the MVS™ SETXCF START,REBUILD command to expand the GBP coupling facility structure. If you rebuild, you can use the ALTER GROUPBUFFERPOOL command to lower the RATIO so that a higher percentage of the GBP storage is given to data entries over directory entries.
  • If you are running on MVS 5.2 or a subsequent release, you can use the MVS SETXCF START,ALTER command to expand the size of the GBP (the maximum size to which you can expand is determined by the SIZE parameter in the CFRM policy that was used to allocate the GBP).

If you don't do anything to relieve the storage shortage, message DSNB325A appears if the GBP reaches 90 percent full.

Message DSNB327I appears when the GBP storage shortage is relieved.

You can monitor the amount of GBP storage in use with the DISPLAY GBPOOL command and with the Db2 statistics trace. Monitor the castout activity to ensure that castouts are keeping up with the rate of GBP-write activity. You can use Performance trace classes 20 and 21 (specifically, IFCIDs 0261, 0262 and 0263) to do more detailed monitoring of the Db2 castout processing.