IBM Z10 EC manual Coupling Facility Control Code Cfcc Level

be dynamically routed to the z/OS image most capable of handling the work. This dynamic workload balancing, along with the capability to have read/write access data from any- where in the Parallel Sysplex cluster, provides scalability and availability. When confi gured properly, a Parallel Sys- plex cluster is designed with no single point of failure and can provide customers with near continuous application availability over planned and unplanned outages.

With the introduction of the z10 EC, we have the concept of n-2 on the hardware as well as the software. The z10 EC participates in a Sysplex with System z10 BC, System z9, z990 and z890 only and currently supports z/OS 1.8 and higher.

For detailed information on IBM’s Parallel Sysplex technol- ogy, visit our Parallel Sysplex home page at http://www- 03.ibm.com/systems/z/pso/.

Coupling Facility Control Code (CFCC) Level 16

CFCC Level 16 is being made available on the IBM System z10 EC.

Improved service time with Coupling Facility Duplex-

ing enhancements: Prior to Coupling Facility Control Code (CFCC) Level 16, System-Managed Coupling Facility (CF) Structure Duplexing required two duplexing protocol exchanges to occur synchronously during pro- cessing of each duplexed structure request. CFCC Level 16 allows one of these protocol exchanges to complete asynchronously. This allows faster duplexed request ser- vice time, with more benefi ts when the Coupling Facilities are further apart, such as in a multi-site Parallel Sysplex environment.

List notification improvements: Prior to CFCC Level 16, when a shared queue (subsidiary list) changed state from empty to non-empty, the CF would notify ALL active con- nectors. The fi rst one to respond would process the new message, but when the others tried to do the same, they would fi nd nothing, incurring additional overhead.

CFCC Level 16 can help improve the effi ciency of coupling communications for IMS Shared Queue and WebSphere MQ Shared Queue environments. The Coupling Facility notifi es only one connector in a sequential fashion. If the shared queue is processed within a fi xed period of time, the other connectors do not need to be notifi ed, saving the cost of the false scheduling. If a shared queue is not read within the time limit, then the other connectors are notifi ed as they were prior to CFCC Level 16.

When migrating CF levels, lock, list and cache structure sizes might need to be increased to support new function. For example, when you upgrade from CFCC Level 15 to Level 16 the required size of the structure might increase. This adjustment can have an impact when the system allocates structures or copies structures from one coupling facility to another at different CF levels.

The coupling facility structure sizer tool can size struc- tures for you and takes into account the amount of space needed for the current CFCC levels.

Access the tool at: http://www.ibm.com/servers/eserver/ zseries/cfsizer/.

CFCC Level 16 is exclusive to System z10 and is sup- ported by z/OS and z/VM for guest exploitation.

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