gtpd1m3dDatabase Reference

Coupling Facility Record Lock Support

The limited lock facility (LLF) and the concurrency filter lock facility (CFLF), which are two external lock facilities (XLFs) supported by the TPF system, were required to control access to data shared by two or more processors in a loosely coupled complex. CF record lock support provides the option of using one or more CFs as XLFs.

CF record lock support offers significant flexibility in using CFs as XLFs in your CF locking configuration. Your CF locking configuration may be dynamically modified by adding or deleting CFs. When a CF is added to or deleted from the CF locking configuration, the TPF system automatically redistributes any CF locks to balance the locking workload across all available CFs. You can add as many as 32 CFs to your CF locking configuration for a high degree of availability. The CFs in your CF locking configuration can be used in addition to or instead of LLF and CFLF. In addition, the CFs in your CF locking configuration can simultaneously be used for nonlocking workloads. Using CFs in a locking configuration can eliminate the need for LLF or CFLF XLFs, giving you greater flexibility when selecting and implementing new module control units (CUs).

All online modules in a loosely coupled complex must use an XLF for locking to control access to shared data. You may specify which online modules will use CFs for locking even if those modules are connected to a CU with an LLF or CFLF. Modules can be migrated to use CFs for locking either individually, in groups, or by migrating all online modules at once. Note that the lock residency of any duplicate module is configured automatically to be identical to that of the corresponding prime module.

See TPF Migration Guide: Program Update Tapes for more information about CF record lock support and seeTPF Concepts and Structures for more information about CF record lock support, the LLF, CFLF, and XLFs.