Chapter 1. Introduction to the Parallel Sysplex 29
1.7 Other connection services
Besides connecting to and disconnecting from a structure, XES connection services also
support several other request types.
When the structure is no longer required, it can be deleted. This may be done automatically if
the structure is not persistent when there are no more active or failed persistent connections.
If the structure is persistent, and therefore not deleted when all connections are gone, it may
be deleted using an operator command. The command will only work if there are no
connections. When this command is entered, XCF will invoke XES connection services to
delete the structure.
Structure event notification
As mentioned earlier, all connectors to a structure belong to an XCF group. For example, all
IRLMs connected to a lock structure belong to the same XCF group. When connection
services are invoked to connect to the structure, an
event exit is specified. Certain events
related to the structure itself (as opposed to the data within the structure) cause this event exit
to be driven. Examples of events that drive this exit are:
New connection to a structure
Disconnection or failed connection
Loss of connectivity by any connector
Structure or Coupling Facility failure
Several rebuild, alter, and duplexing events
Structure rebuild is the construction of a new instance, or a secondary instance, of a
structure. When a connector connects to a structure, it may specify one or more of the
ALLOWREBLD=YES means that the connector will support user-managed rebuild of the
ALLOWDUPREBLD=YES means that the connector will support user-managed duplexing
of the structure.
ALLOWAUTO=YES means that the connector will support system-managed processes,
which include system-managed rebuild and system-managed duplexing. These processes
also require the CFRM couple data set to be formatted to support system-managed
processes (SMREBLD and SMDUPLEX) specified in the CDS format utility.
There must be at least one active connector to the structure and all connectors must agree to
coordinate the rebuild process. Briefly, this means that the connectors coordinate to quiesce
activity, to connect to the new instance, to propagate data to the new structure instance, and
then to signal completion, at which time the original instance is deallocated (deleted).
User-managed rebuild can be used to move a structure from one Coupling Facility to another,
or to recover from a loss of connectivity or structure failure. It may be initiated by one of the
connectors, or by operator command: