Average Synchronous Write (ms) - Database

Identifier:db2.db_avg_sync_write_time

Database Object Monitored:Database

Category:Buffer Pool and I/O

Description:Average synchronous write time

Equation:db2. db_sync_write_time / db2. db_sync_data_writes

Usage Notes:This variable indicates the time that your application must wait for synchronous I/O write activity.

You may be able to decrease the synchronous write time by using more asynchronous writes, which are triggered by page cleaners (see "Managing the Database Buffer Pool" in the Administration Guide). Page cleaners can be triggered because:

• The dirty page threshold chngpgs_thresh has been exceeded, indicated by a low pool_drty_pg_thrsh_clns value
• A page was required (page stealing), indicated by a low pool_drty_pg_steal_clns value
• The log space threshold was exceeded, indicated by a low pool_lsn_gap_clns value

The first occurrence could indicate that the waits for synchronous I/O may be due to insufficient page cleaning. In this case you should increase the database configuration parameter chngpgs_thresh.

The second occurrence could indicate that the waits for synchronous I/O may be due to insuffecient page cleaning. In this case you should increase the database configuration parameter chngpgs_thresh.

The third occurrence could indicate that the waits for synchronous I/O may be due to insufficient page cleaning. In this case you should increase the database configuration parameter softmax.

Note:

For multiple buffer pools, the data is combined and only the aggregate number is returned.