The Thresh Cleans component displays the percentage of page cleaners invoked because a buffer pool has reached the dirty page threshold limit for the database.
At each refresh, Spotlight captures the percentage of page cleans due to a buffer pool reaching the dirty page threshold. This threshold is set by the CHNGPGS_THRESH database configuration parameter. The CHNGPGS_THRESH parameter is defined as a percentage of the size of the buffer pool. When the number of dirty pages in the buffer pool reaches this parameter percentage, the page cleaners are triggered. If you set this percentage too low, pages might be written out too early, requiring them to be read back in. If this percentage is too high, too many dirty pages accumulate in the buffer, requiring users to write out pages synchronously.
Click the Thresh Cleans component to open the Databases drilldown. This drilldown provides details about database or partition that you are monitoring. The Statistics tab on the drilldown is in immediate focus so you can examine page cleaner statistics in the database.