Verify that you have enough XCF groups and XCF group members
Description
Over time, as various z/OS® functions and applications exploit XCF services, you must ensure that there is enough space in the sysplex couple data set for all the XCF groups and members that are to be defined by the exploiters. It is possible that your sysplex couple data set could contain an inadequate number of XCF groups or members.
Note: Starting
with z/OS V1R13, JES2 is using new XCF groups for its spool migration
enhancement. JES spool migration utilizes tasks on all members of
a MAS to manage the migration of a spool volume's data and the access
to that migrating or migrated data. These various tasks communicate
using messages sent through JESXCF services. The JESXCF services utilize
one XCF group for each active migration to identify what messages
are for which active migration. XCF groups are a limited system resource,
so JES2 limits the number of concurrent active migrations to five.
If you plan to perform spool migrations, verify that you have up
to five XCF groups available if you intend to have up to five spool
migrations active at any given time. JES2 will only utilize the number
of XCF groups available, up to five, for spool migrations.
Table 1 provides more details about this migration action. Use this information to plan your changes to the system.
| Element or feature: | Multiple. |
|---|---|
| When change was introduced: | General migration action not tied to a specific release. |
| Applies to migration from: | z/OS V2R1 and z/OS V1R13. |
| Timing: | Before installing z/OS V2R2. |
| Is the migration action required? | No, but recommended to ensure that you have an adequate number of XCF groups and members formatted in your sysplex couple data sets. |
| Target system hardware requirements: | None. |
| Target system software requirements: | None. |
| Other system (coexistence or fallback) requirements: | None. |
| Restrictions: | None. |
| System impacts: | None. |
| Related IBM® Health Checker for z/OS check: | Use IBM Health Checker for z/OS check XCF_SYSPLEX_CDS_CAPACITY, which checks the adequacy of the number of groups, members, and systems for which a sysplex CDS is formatted. |
Steps to take
Follow these steps:
- Issue the DISPLAY XCF,COUPLE command on your current system. Notice the values of MAXGROUP and PEAK for your sysplex couple data sets. These values show you the maximum number of XCF groups that the couple data sets can support, and the peak number of XCF groups ever in use in the sysplex. Also notice the values of MAXMEMBER and PEAK for your sysplex couple data sets. These values show you the maximum number of members that the couple data set can support in one group, and the greatest number of members ever in use in the largest group in the sysplex.
- If your peak member value is close to the maximum member value, you might want to reformat your sysplex couple data sets to support a larger maximum number of members to be used by any one group.
Reference information
For more information,
see the following references:
- For information about formatting sysplex couple data sets with the MAXGROUP and MAXMEMBER parameters, see z/OS MVS Setting Up a Sysplex.
- For information about the DISPLAY XCF command, see z/OS MVS System Commands.
Reference information
For more information, see the following references:
- For information about formatting sysplex couple data sets with the MAXGROUP and MAXMEMBER parameters, see z/OS MVS Setting Up a Sysplex.
- For information about the DISPLAY XCF command, see z/OS MVS System Commands.