Insufficient CF capacity

If both the ASYNC and SYNC service times for the various structures exceed the recommended values, the first thing to check is the CF utilization. The RMF™ CF Usage Summary Reports shows the AVERAGE CF UTILIZATION of the processors in the CF; see Figure 1 for an example.

Figure 1. Example: RMF CF Usage Report

                                     C O U P L I N G   F A C I L I T Y   A C T I V I T Y
                                                                                                                    PAGE   1
     OS/390                  SYSPLEX UTCPLXJ8            DATE 05/01/1997           INTERVAL 030.00.000
     REL. 01.03.00            RPT VERSION 1.3.0           TIME 16.00.00             CYCLE 01.000 SECONDS
----------------------------------------------------------------------------------------------------------------------------
 COUPLING FACILITY NAME = CF1
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                                             COUPLING  FACILITY  USAGE  SUMMARY
----------------------------------------------------------------------------------------------------------------------------
 STRUCTURE SUMMARY
----------------------------------------------------------------------------------------------------------------------------

                                                   % OF                % OF      AVG    LST/DIR  DATA      LOCK
        STRUCTURE                       ALLOC      CF            #     ALL       REQ/   ENTRIES  ELEMENTS  ENTRIES  RECLAIMS
 TYPE   NAME              STATUS CHG    SIZE       STORAGE     REQ     REQ       SEC    TOT/CUR  TOT/CUR   TOT/CUR

 LIST   IXCPLEX_PATH2     ACTIVE         31M         1.5%   996232    16.3%    553.46    7611      7596       N/A
                                                                                           61        86       N/A
        LG2_DFHLOG_001    ACTIVE         26M         1.3%    44159     0.7%     24.53      21K       85K      N/A
                                                                                           15K       42K      N/A
                                                                                              14K        3         0
 LIST   COUPLE_CKPT1      ACTIVE         13M         0.6%    71760     1.2%     39.87    3192      3182         2
                                                                                         3007      3007         1

 LOCK   IRLMLOCK1         ACTIVE         31M         1.5%     1627K   26.7%    904.00     114K        0      4194K
                                                                                           27         0       384

 CACHE  RLSCACHE01        ACTIVE        244M        12.1%   714874    11.7%    397.15     323K       92K      N/A
                                                                                          323K       92K      N/A
        VSAMCACHE1        ACTIVE         34M         1.7%   657723    10.8%    365.40     183K        0       N/A
                                                                                          101K        0       N/A

  PROCESSOR SUMMARY
 -----------------------------------------------------------------------------------------------------------

  AVERAGE CF UTILIZATION  (% BUSY)           17.3      LOGICAL PROCESSORS:   DEFINED   6    EFFECTIVE   6.0

Generally, best performance from the CF is obtained when the average CF utilization is less than 50%. If the utilization exceeds this, there are various actions that can be taken, depending on the environment.

Verify that the number of logical processors defined is correct. There have been instances when the CF was configured to one logical processor during service and was not reset.
Verify that the processor resource allocated to the CF is what you expected. If this is an LPAR environment and the CF partition is sharing CPs, the processor resource will be limited by the definition of the WEIGHT and CAP parameters and contention from the other partitions. If this CF resides on a processor with MVS™ images, information about the WEIGHT and CAP definitions can be found on the CPU Partition Data Report. The amount of processor resource available to the CF is reported as LOGICAL PROCESSORS EFFECTIVE. You will get the best response time by dedicating CP(s) to the CF partition.
If you have multiple stand-alone CFs in your configurations, check the distribution of structures. If one CF has much higher utilization than the other, redistribute the structures based on ALLOC SIZE and # REQ.
If all else fails, you can increase the capacity of the CF by adding CPs or obtaining an additional CF.