Self-tuning memory overview

Self-tuning memory simplifies the task of memory configuration by automatically setting values for memory configuration parameters and sizing buffer pools. When enabled, the memory tuner dynamically distributes available memory resources among the following memory consumers: buffer pools, locking memory, package cache, and sort memory.

Self-tuning memory is enabled through the self_tuning_mem database configuration parameter.

The following memory-related database configuration parameters can be automatically tuned:
  • database_memory - Database shared memory size
  • locklist - Maximum storage for lock list
  • maxlocks - Maximum percent of lock list before escalation
  • pckcachesz - Package cache size
  • sheapthres_shr - Sort heap threshold for shared sorts
  • sortheap - Sort heap size

Starting withDb2® Cancun Release, each member in a Db2 pureScale® environment has its own self-tuning memory manager (STMM) tuner.

Starting withDb2 version 10.5 Fix Pack 5, the following memory-related database configuration parameters can also be automatically tuned in a Db2 pureScale environment:
  • cf_db_mem_sz - CF Database memory
  • cf_gbp_sz - Group buffer pool
  • cf_lock_sz- CF Lock manager
  • cf_sca_sz - Shared communication area