INGCF DRAIN

Purpose

The DRAIN function of INGCF facilitates the removal of a coupling facility from the sysplex, for example, for maintenance purposes. With this option, you can perform the following sequence of tasks:

  1. Display information for all allocated structures of the coupling facility.
  2. Put the coupling facility into maintenance mode if the MAINT function is available.
  3. Rebuild all rebuildable structures on another coupling facility, and delete instances of structures on the target coupling facility that are being duplexed on another coupling facility.
    Notes:
    1. The scope of the structures that can be rebuilt depends on the release level of the sysplex members.
    2. INGCF DRAIN rebuilds structures one at a time (SETXCF START,REBUILD,STRNAME=), not globally (SETXCF START,REBUILD,CFNAME=), and always on a coupling facility that is different from the target coupling facility (LOCATION=OTHER).
    3. Generally, you should be aware that it is XES that performs the actual rebuild. Not all of the factors that XES takes into account when allocating a structure are accessible to SA z/OS®. Therefore, a rebuild request for a structure that should be rebuildable according to its condition can fail in certain rare cases.
  4. Force the deletion of structures that have no active connectors and cannot be rebuilt.
    Note: There are structures that you can neither rebuild nor delete with the force action. Included are the structures that have at least one active connector and do not support rebuild. To remove such structures, first disconnect all active connectors, and then delete the structure manually if it is persistent or has persistent connections.
  5. When the coupling facility is not in maintenance mode, disconnect the coupling facility from the systems that it is connected to.
  6. Inactivate the target coupling facility.

INGCF DRAIN ensures that these actions are performed in the correct order, as specified above.

Actions

The following F-keys are supported:

*REBUILD (F10)
Starts the rebuild of structures that can be rebuilt on another coupling facility. Thus, a rebuild is only initiated for structures whose preference list contains more than one coupling facility.

There are two methods for rebuild, user-managed and system-managed rebuild. User-managed rebuild is supported for all release levels. System-managed rebuild is only available with systems that have been enabled by formatting the CFRM couple data sets with the specification:

ITEM NAME(SMREBLD) NUMBER(1)

System-managed rebuild is only performed when the requirements for user-managed rebuild are not met. This applies, for example, to structures without active connectors.

The REBUILD action also deletes all structure instances on the target coupling facility that are being duplexed on another coupling facility.

Note: The REBUILD action deallocates structures with the condition No active connection exists.. See No active connection exists..
*FORCE (F5)
Forces the deallocation of structures with one of the following conditions:
  • No connection exists.
  • No alternate coupling facility for structure with no active connections.
  • No alternate coupling facility for structure with no connections.

This action is only made available after all structures that can be rebuilt have been rebuilt.

*MAINTON (F5)
Puts the coupling facility into maintenance mode.

Note that this function is only available before you start the rebuild process. Once you have started the rebuild process and you want to put the coupling facility into maintenance mode you need to issue the command INGCF MAINT cf_name MODE=ON.

*DRAIN (F4)
Disconnects the coupling facility from its connected systems by setting the sender paths OFFLINE.

This action is only enabled after all structures of the target coupling facility have been removed to another coupling facility or deallocated. Note that structures that have active connectors but do not support rebuild cannot be removed with F10 or F5. They must be deallocated manually before executing this step is enabled.

*SHUTDOWN (F11)
This action inactivates the coupling facility. It is only made available when all connections between the coupling facility and the systems of the sysplex have been disconnected.
Note: This function key is unavailable when running on a z/OS image that runs under z/VM®.

Note that these actions can only be performed if INGCF DRAIN is issued in full mode. In line mode, only the display function is available.

To avoid performance degradation due to multiple rebuild processes, or unpredictable results due to multiple executions of an action, all actions are locked. Therefore, an action is rejected if any lock exists even if the action does not affect the action currently being performed. Because the action can take a long time it is also executed asynchronously on a dedicated autotask, preventing the operator from being blocked. To check progress, use the refresh function (F9).