IMS restart and global resource status in an IMSplex that uses RM

If you are operating in an IMSplex environment that uses the Resource Manager (RM) component of the Common Service Layer, you need to understand how restarting an IMS system affects both the global and local status information of the IMS resources that the restarting IMS system shares with the rest of the IMSplex.

The first IMS system to start in an IMSplex sets the PLEXPARM values that the IMS system knows about in RM. Subsequent IMS systems that start in the IMSplex obtain the PLEXPARM values by reading the PLEXPARM entry in RM. Subsequent IMS systems either use the PLEXPARM entry in RM if it has a value or update the PLEXPARM value in RM if they introduce a PLEXPARM variable.

When an IMS system restarts, if global status is maintained for a resource type, the type of restart determines how the global status is applied at the restarting IMS. For example:

• For cold starts, the global status of databases, areas, and transactions takes precedence.
• For warm starts, the restarting IMS system first applies the local status saved in the log records and then applies the global status stored in RM only if it changed while the IMS system was down.
• For emergency restarts, the restarting IMS system first applies the local status saved in the log records and then applies the global status stored in RM only if it changed while the IMS system was down.
• For COLDSYS emergency restarts, the global status of databases, partitions, areas, and transactions takes precedence.
• For COLDBASE emergency restarts, the global status of databases, partitions, and areas take precedence.
• For COLDCOMM emergency restarts, the global status of transactions takes precedence.

Any error reading the global status of resources in RM during IMS initialization results in a message DFS3500W that states that the maintenance in RM of the global resource status is disabled for the specified resource type.

Before attempting to restart IMS again, take one of the following actions:

1. Cancel IMS or shutdown IMS after restart completes. After the error condition reported in the DFS3308W message is fixed, restart IMS. IMS will be synchronized with RM status, and no additional action is required.
2. Allow the IMS restart to complete, then take the following actions:
   • Issue the appropriate UPDATE IMS SET(PLEXPARM) command to enable global status at this IMS.
   • Issue the appropriate QRY TRAN|DB|AREA SHOW(GLOBAL) commands to see the resources with global status.
   • Issue appropriate command with the SCOPE(ACTIVE) parameter to ensure that the IMS is synchronized with RM status.