Where Db2 looks for a page

Db2 searches for pages in buffer pools and on disk in a specific order.

Db2 searches for pages in this order:
  1. In the local buffer pool. If the page is invalid, Db2 refreshes the page from the group buffer pool (or disk).
  2. In the group buffer pool. Db2 checks the group buffer pool for a page if the page set is defined as GBPCACHE ALL or if the page set or the partition is GBP-dependent, unless one of the following conditions is true:
    • Group buffer pool is defined as GBPCACHE(NO).
    • Page set is defined as GBPCACHE NONE.
    • Page set is defined as GBPCACHE SYSTEM and the page being read is not a space map page.
  3. On disk. If the page is not in the group buffer pool, Db2 refreshes the page in the buffer pool from disk.

For duplexed group buffer pools, read activity occurs only against the primary structure.