Tablespaces: Buffer Pool (DB2 UDB for UNIX and Windows) (SAP Library

Tablespaces: Buffer Pool (DB2 UDB for UNIX and Windows)

To display information on buffer pool activity for your selected tablespace(s), call the DBA Cockpit.

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1. In the navigation frame, choose Performance ®Tablespaces.

The Tablespace Snapshot screen appears.

2. To display more detailed information, select one or more tablespaces and choose This graphic is explained in the accompanying text Details.

A detail Tablespace Snapshot screen appears.

3. Choose Buffer Pool.

If you have selected more than one tablespace, you can use the page buttons on the screen to navigate between them.

Field	Description
*Tablespace*
Name	Name of the tablespace
*Buffer Quality*
Overall Buffer Quality	Indicates percentage at which the data is read from the buffer pool, rather than directly from the hard disk. This is calculated using the following formula: (logical reads - physical reads) / (logical reads) * 100
Data Hit Ratio	Indicates percentage at which data (without index data) is read from the buffer pool, rather than directly from the hard disk
Index Hit Ratio	Indicates percentage at which index data is read from the buffer pool, rather than directly from the hard disk
*Average Time*
Physical Reads	Average time in milliseconds required to read data from disk into the buffer pool
Physical Writes	Average time in milliseconds required to write data from the buffer pool to disk
*Data*
Logical Reads	Number of read accesses to data in the buffer pool
Physical Reads	Number of read accesses to data on disk (I/O). The value includes the number of physical reads that were performed synchronously (by the database manager agents) and asynchronously (by the I/O servers).
Physical Writes	Number of write accesses to data on disk (I/O). The value includes the number of physical writes that were performed synchronously (by the database manager agents) and asynchronously (by the I/O cleaners).
Synchronous Reads	Number of read accesses to data on disk (by agents)
Synchronous Writes	Number of write accesses to data on disk (by agents)
Temporary Logical Reads	Number of logical read requests that required I/O to get data pages into the temporary tablespace
Temporary Physical Reads	Number of physical read requests that required I/O to get data pages into the temporary tablespace
*Index*
Logical Reads	Number of read accesses to index data in the buffer pool
Physical Reads	Number of read accesses to index data on disk (I/O). Since index data is read only by the database manager agents, this value includes the number of synchronously read index pages.
Physical Writes	Number of write accesses to index data on disk (I/O). The value includes the number of physical writes that were performed synchronously (by the database manager agents) and asynchronously (by the I/O cleaners).
Synchronous Reads	Number of read accesses to index data on disk (by agents)
Synchronous Writes	Number of write accesses to index data on disk (by agents)
Temporary Logical Reads	Number of logical read requests that required I/O to get index pages into the temporary tablespace
Temporary Physical Reads	Number of physical read requests that required I/O to get index pages into the temporary tablespace