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Snapshot Level Database Table Space |
Logical Data Grouping dbase tablespace bp_info |
Monitor Switch Buffer Pool Buffer Pool Buffer Pool |
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Resettable |
Yes |
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Event Type Database Table Space |
Logical Data Grouping db_event tablespace_event |
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Element Name Element Type |
pool_async_data_writes counter |
Description: The number of times a buffer pool data page was physically written to disk by either an asynchronous page cleaner, or a prefetcher. A prefetcher may have written dirty pages to disk to make space for the pages being prefetched.
Usage: You can use this element with "Buffer Pool Data Writes" to calculate the number of physical write requests that were performed synchronously (that is, physical data page writes that were performed by database manager agents). Use the following formula:
buffer pool data writes - buffer pool asynchronous data writes
By comparing the ratio of asynchronous to synchronous writes, you can gain insight into how well the buffer pool page cleaners are performing. This ratio can be helpful when you are tuning the num_iocleaners configuration parameter.
For more information about asynchronous page cleaners, see the Administration Guide.