RO SWITCH TIME field (PCLOSET subsystem parameter)
The PCLOSET subsystem parameter specifies the number of minutes that a partition or page set remains read-write after it is updated. After the specified number of minutes, Db2 converts the set or partition to read-only.
| Acceptable values: | 1–32767 |
|---|---|
| Default: | 45 (minutes) |
| Update: | option 43 on panel DSNTIPB |
| DSNZPxxx: | DSN6SYSP PCLOSET |
- 1–32767
- The number of minutes that a page set or partition remains read-write after it is updated. After the specified number of minutes, Db2 converts the set or partition to read-only.
This value is used in conjunction with the value of the RO SWITCH CHKPTS field. If the condition for RO SWITCH CHKPTS or RO SWITCH TIME is met, the page set or partition is converted from read-write to read-only.
For NOT LOGGED table spaces, Db2 converts the page set or partition from read-write to read-only after one minute, regardless of the value of RO SWITCH TIME.
Having Db2 switch an infrequently updated page set from read-write to read-only can be a performance benefit for recovery, logging, and for data sharing processing.
You can override the PCLOSET value for a specific buffer pool by issuing an ALTER BUFFERPOOL command with the VPCLOSET option. In the DISPLAY BUFFERPOOL command output, the DSNB404I message displays the value in effect for the buffer pool, which can be the value specified in the VPCLOSET option, or the PCLOSET subsystem parameter value. If the VPCLOSET option was not used, or it was set to 0, for the buffer pool the PCLOSET value is displayed.