Buffer pools are areas of virtual storage in which DB2® temporarily stores pages of table spaces or indexes. Access to data in this temporary storage is faster than accessing data on a disk.

When an application program accesses a row of a table, DB2 retrieves the page that contains the row and places the page in a buffer. If the required data is already in a buffer, the application program does not need to wait for it to be retrieved from disk, so the time and cost of retrieving the page is reduced.

Buffer pools require monitoring and tuning. The size of buffer pools is critical to the performance characteristics of an application or group of applications that access data in those buffer pools.

DB2 lets you specify default buffer pools for user data and for indexes. A special type of buffer pool that is used only in Parallel Sysplex® data sharing is the group buffer pool, which resides in the coupling facility. Group buffer pools reside in a special PR/SM™ LPAR logical partition called a coupling facility, which enables several DB2 subsystems to share information and control the coherency of data.

Buffer pools reside in the DB2 DBM1 primary address space. This option offers the best performance. The maximum size of a buffer pool is 1 TB.