IMS in the Parallel Sysplex Volume I: Reviewing the IMSplex Technology

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.

Structure delete

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.

SETXCF FORCE,STRUCTURE,STRNAME=structure-name

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

򐂰 Existing connections

򐂰 Disconnection or failed connection

򐂰 Loss of connectivity by any connector

򐂰 Structure or Coupling Facility failure

򐂰 Several rebuild, alter, and duplexing events

Structure rebuild

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

following parameters.

򐂰 ALLOWREBLD=YES means that the connector will support user-managed rebuild of the

structure.

򐂰 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.

User-managed rebuild

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:

SETXCF START,REBUILD,STRNAME=structure-name<,LOC=OTHER>