DB2 Version 9.7 for Linux, UNIX, and Windows

log_held_by_dirty_pages - Amount of Log Space Accounted for by Dirty Pages monitor element

The amount of log (in bytes) corresponding to the difference between the oldest dirty page in the database and the top of the active log.

Element identifier: log_held_by_dirty_pages
Element type: watermark

Table 1. Snapshot Monitoring Information
Snapshot Level	Logical Data Grouping	Monitor Switch
Database	dbase	Basic

Table 2. Event Monitoring Information
Event Type	Logical Data Grouping	Monitor Switch
Database	event_db	-

Usage

When the snapshot is taken, this value is calculated based on conditions at the time of that snapshot.

Use this element to evaluate the effectiveness of page cleaning for older pages in the buffer pool.

The cleaning of old pages in the buffer pool is governed by the softmax database configuration parameter. If the page cleaning is effective then log_held_by_dirty_pages should be less than or approximately equal to:

  (softmax / 100)  *  logfilsiz * 4096

If this statement is not true, increase the number of page cleaners (num_iocleaners) configuration parameter.

If the condition is true and it is desired that less log be held by dirty pages, then decrease the softmax configuration parameter.