The following examples outline some steps an operator can take to prepare a coupling facility for removal from the configuration and then subsequently return it to the configuration after maintenance procedures have been completed. In the example coupling facility CF1 is the coupling facility being removed, leaving coupling facilities CF2 and CF3 in the configuration. To prepare for this, the structures in CF1 must be moved to one of the other coupling facilities before CF1 can be removed from the configuration.

1. Place the coupling facility in maintenance mode: In preparation for removing coupling facility CF1 from the sysplex, you can place it in maintenance mode. This step prevents systems from allocating any structures in CF1 while you prepare to take it down for upgrade procedures. Issue operator command:

   SETXCF START,MAINTMODE,CFNAME=CF1

2. Move structures out of CF1: The operator can move structures in CF1 to another coupling facility with any of the following commands:
   • SETXCF START,REBUILD,CFNAME=CF1,LOCATION=OTHER

     The LOCATION=OTHER specification indicates that each structure is to be rebuilt in a different coupling facility in each structure's preference list. If no other suitable coupling facility exists in the CFRM policy for a particular structure, it might be necessary to update the CFRM policy so that a coupling facility can be found.

   • SETXCF START,REBUILD,STRNAME=strname,LOCATION=OTHER

     Note that XCF signalling structure must be rebuilt one at a time.

   • SETXCF STOP,REBUILD,DUPLEX,CFNAME=CF1

     This method works because when a duplexing rebuild is stopped with CFNAME specified, the instance allocated in the specified coupling facility in NOT kept.

   Once all structure have been removed from CF1, it can be removed from the configuration for maintenance.

3. Take the coupling facility out of maintenance mode: If you put coupling facility CF1 in maintenance mode, you must take it out of maintenance mode before you try to move structures back into it. If you don't take it out of maintenance mode first, it will still be on the list of undesirable coupling facilities and it will be impossible to move structures into it.
   Use the following command to take a coupling facility out of maintenance mode: Issue operator command:

   SETXCF STOP,MAINTMODE,CFNAME=CF1

4. Move structures back into CF1 when the coupling facility is back up: After CF1 is returned to the sysplex configuration, you can use either the REALLOCATE process or the POPULATECF function to move structures back into CF1. The REALLOCATE process and the POPULATECF function are mutually exclusive. Use one of the following options:
   • SETXCF START,REALLOCATE

     Reallocates structures into all coupling facilities, including CF1, as appropriate based on the current CFRM policy and structure allocation criteria. The REALLOCATE process ensures that only those structure instance(s) allocated in a "less suitable" coupling facility have structure rebuild processing initiated to adjust the location or activate a pending policy change.

     Thus, the entire set of allocated structures (simplex or duplexed) in the CFRM active policy are eligible to be evaluated for placement in CF1 and any other coupling facility in use by the sysplex, even if they were not part of the original CF1 evacuation. As each allocated structure in the CFRM policy is examined, messages are issued to the operator or written to the hardcopy log to track the processing as follows:

     • IXC574I showing the current location of instance(s), the policy information used, and the results of applying the XCF allocation algorithm.
     • When a structure does not have REALLOCATE processing attempted, IXC544I is issued.
     • When a structure is the target of REALLOCATE processing, messages for structure rebuild processing (IXC52nI and IXC57nI) and the deallocation process (IXC579I) are issued as the necessary step(s) are taken to adjust the location or activate a pending policy change.

     When the REALLOCATE processing finishes, messages IXC545I and IXC543I are issued to the operator.

   • SETXCF START,REBUILD,POPULATECF=CF1

     Repopulates the CF1 coupling facility with structures. The POPULATECF keyword ensures that only those structures that have CF1 as a higher coupling facility in their preference list than where the structure is currently allocated will be rebuilt in CF1.

     Thus, the entire set of allocated simplex structures in the CFRM active policy are eligible to be rebuilt in CF1, even if they were not part of the original CF1 evacuation.

     As each structure in the CFRM policy is examined, messages to the operator indicate:

     • Whether a structure is eligible to be rebuilt.
     • Whether a structure is not eligible to be rebuilt because CF1 is not in the structure's preference list.
     • Whether the structure is to remain in its current location because, although the structure might be eligible to be rebuilt, CF1 is not higher in the structure's preference list than that in which the structure already resides or there are other reasons why CF1 is not more suitable.
     • The successful rebuild of a structure into CF1.

     Note that after the population of CF1, if it is necessary to redistribute the structures for a better sysplex balance, the preference lists in the CFRM policy could be updated. Once the updated CFRM policy is activated, the POPULATECF function could again be used for CF1 or any other coupling facility to redistribute the structures.