Group buffer pool checkpoint

When a group buffer pool is damaged, all changed data that belong to GBP-dependent page sets must be recovered to the page sets from the Db2 logs.

The number of log records that need to be applied to the page set is determined by the frequency of the group buffer pool checkpoint. Group buffer pool checkpoint is the process of writing all changed pages in the group buffer pool (only the primary one, if duplexed) to the page set. The purpose of the checkpoint is to reduce the amount of time needed to recover data in a group buffer pool. At group buffer pool checkpoint, Db2 records, in the member BSDSs and SCA, the log record sequence number from which group buffer pool recovery would need to take place. Group buffer pool checkpoint does not record anything in the log.

The group buffer pool checkpoint is triggered by the structure owner. The structure owner is usually the first member that connects to this group buffer pool, although the ownership can change over time. Message DSNB798I in the DISPLAY GROUPBUFFERPOOL command output shows which member is the current structure owner.