Buffer Pools

The Buffer Pools window shows information about the Buffer Pools activity. 

The grid located at the top of the window shows each database partition. It allows you to filter buffer pools for each database partition.

The next grid shows each individual Buffer Pool with the following information for each one:

Name The name of the buffer pool.
Partition Database partition number.
DB Name The real name of the database for which information is collected or to which the application is connected. This is the name the database was given when created.
Size Current buffer pool size.
Use Count The number of table spaces using this buffer pool.
Files Closed The total number of database files closed.
Pg from vectored ios The total number of pages read by vectored I/O into the page area of the buffer pool.
Pg from block ios The total number of pages read by block I/O into the block area of the buffer pool.

By default, the last snapshot is displayed in the grid. Use the slidder (or the arrow buttons) located at the top of the grid to navigate through the collected snapshots. In monitoring, the "Update" button must be unchecked to be able to navigate through the collected snapshots.

Select one or more Buffer Pools in the grid (Check box at the left of the grid) to update the graphes located at the bottom of the window. If several Buffer Pools are selected, the statistics are aggregated.

Hit Ratio (%)

Overall The buffer pool hit ratio indicates the percentage of time that the database manager did not need to load a page from disk in order to service a page request because the page was already in the buffer pool. The greater the buffer pool hit ratio, the lower the frequency of disk I/O.
Index Indicates the percentage of all read request for index pages that were satisfied by a page found in the buffer pool.

Avg Pool I/O Time (ms)

Write Provides the average amount time spent physically writing data or index pages from the buffer pool to disk.
Read Indicates the average amount time spent reading in data and index pages from the table space containers (physical) for all types of table spaces.
R Async Indicates the average amount time spent reading in data and index pages from the table space containers (physical) by asynchronous engine dispatchable units (EDUs) for all types of table spaces.
W Async The average elapsed time spent writing data or index pages from the buffer pool to disk by database manager page cleaners.
R Direct The average elapsed time required to perform the direct reads.
W Direct The average elapsed time required to perform the direct writes.

Async Not Read (%)

The percentage of asynchronously read pages that are never read.

Write (Unit/s)

Data Indicates the number of times a buffer pool data page was physically written to disk.
D Sync The number of physical data write requests were performed synchronously. That is, physical data page writes that were performed by database manager agents.
Index Indicates the number of times a buffer pool index page was physically written to disk.
I Sync The number of physical index write requests were performed synchronously. That is, physical index page writes that were performed by database manager agents.
Total Indicates the number of times a buffer pool data page, data page for an XML storage object (XDA), index page were physically written to disk.
T Sync The number of physical data, index write requests performed synchronously (include on XML storage object data pages). That is, physical page writes that were performed by database manager agents.
Direct The number of write operations that do not use the buffer pool.

Read (Unit/s)

D Logical Indicates the number of data pages which have been requested from the buffer pool (logical) for temporary, regular and large table spaces.
D Physical Indicates the number of data pages read in from the table space containers (physical) for temporary, regular and large table spaces.
D Sync Indicates the number of physical reads that were performed synchronously (that is, physical data page reads that were performed by database manager agents).
I Logical Indicates the number of index pages which have been requested from the buffer pool (logical) for temporary, regular and large table spaces.
I Physical Indicates the number of index pages read in from the table space containers (physical) for temporary, regular and large table spaces.
I Sync Indicates the number of physical reads that were performed synchronously (that is, physical index page reads that were performed by database manager agents).
T Log Indicates the number of data pages, pages for XML storage object (XDA) data, index pages which have been requested from the buffer pool (logical) for temporary, regular and large table spaces.
T Phys Indicates the number of data pages, data pages for an XML storage object (XDA), index pages read in from the table space containers (physical) for temporary, regular and large table spaces.
T Sync The number of physical reads performed synchronously (include on XML storage object data pages) (that is, physical data and index page reads that were performed by database manager agents (include on XML data)).
Direct The number of read operations that do not use the buffer pool.

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