Buffer Pool Page
A buffer pool is a distinct area of the buffer cache within the SGA (System Global Area) that stores buffers for nominated tables accessed by I/O sessions. The Buffer Pool page displays I/O statistics that may be used to identify bottlenecks within the buffer pool.
This information is shown in four charts, and each chart contains data for the allocated buffer pools.
- Most systems need only a single DEFAULT buffer pool.
- A separate KEEP pool (if allocated) can be used store blocks from segments that are accessed frequently and that should remain cached for quick reference.
- The RECYCLE pool (if allocated) is used to store blocks from segments that are accessed rarely and that do not need to be kept in cache.
To open the Buffer Pool Page
- Select the Spotlight on Oracle RAC connection in the Spotlight Browser.
-
Click I/O | Buffer Pool.
Charts on the Buffer Pool Page
| Chart | Description |
|---|---|
|
Physical reads |
The rate at which requested data blocks are read physically from datafiles on disk into the specified buffer pool. |
|
Logical reads |
The rate at which data blocks are requested in the specified buffer pool. If logical reads cannot be satisfied by blocks already in the buffer cache, they must be read physically from datafiles on disk. |
|
Miss rate |
The miss rate in each buffer pool over time. The miss rate is the percentage of logical reads that cannot be satisfied by blocks already in the buffer cache, and that therefore require physical reads. |
|
Block waits |
The rate of waits for blocks in each buffer. This includes free buffer waits, write complete waits, and buffer busy waits. For a description of each of these conditions, see Deal With Wait Events. |