Read operations

In a data sharing environment, the process of reading data is different from the process in a non-data sharing environment.

Where Db2 looks for a page
Db2 searches for pages in buffer pools and on disk in a specific order.
Testing the page validity
Part of the process of controlling cache coherency is testing to see if a page that is referenced in the buffer pool must be refreshed from the group buffer pool or disk because it might no longer be the most current version of the data.
Prefetch processing
Db2 prefetch processing for GBP-dependent page sets and partitions varies depending on the level of coupling facility (CFLEVEL) in which the group buffer pool is allocated.
Use of caching for group buffer pools
You can cache pages in the group buffer pool as they are read into a member's local buffer pool by specifying GBPCACHE ALL when you create or alter a table space or index.

Parent topic: Tuning group buffer pools