Controlling Data Sharing

Controlling data sharing involves:

• "Monitoring the Data-Sharing System"

• "Controlling Data Sharing Using DBRC" on page 431

Monitoring the Data-Sharing System

To monitor data sharing, you obtain information on the status of the IRLM, IMS subsystems and databases, the RECON data sets, and coupling facility structures that are participating in data sharing.

Obtaining the Status of IRLM Activity

To display the status of an IRLM on either your system or on another connected system, enter the following z/OS command:

 MODIFY irlmproc, STATUS, irlmx 

irlmproc is the name of the procedure that you used to start the IRLM, and irlmx is the name of the IRLM whose status you want to display. This command returns:

• The IMS IDs of IMS subsystems using this IRLM.

• The number of locks that are held and waiting for each subsystem on this IRLM.

• Identification of this IRLM: its subsystem name and IRLM number.

You can use the ALLD keyword to display the names and status of every IMS identified to an IRLM in a data-sharing group. Or, you can use the ALLI keyword to display the names and status of every IRLM in a data-sharing group.

Related Reading: For a complete description of the commands for the IRLM, see IMS Version 9: Command Reference.

Displaying Components and Resources

Monitoring components and resources in a data-sharing environment requires the same types of procedures as in a non-data-sharing environment. For more information about monitoring, see "Monitoring the System" on page 405.

Table 24-10 lists keywords for the /DISPLAY command that you can use to obtain information about various IMS resources.

Table 24-10. /DISPLAY Command Keywords That Provide Information about IMS Resources

Resources	/DISPLAY Command Keywords
Active control regions	ACTIVE REGION
Active jobs	ACTIVE
Programs, transactions, and conversations	CONVERSATION PROGRAM PSB STATUS PROGRAM STATUS TRANSACTION SYSID TRANSACTION TRANSACTION
Databases	DATABASE AREA STATUS DATABASE
Terminals, lines, links, and nodes
	ACTIVE DC ASSIGNMENT LINE ASSIGNMENT LINK ASSIGNMENT NODE LINE LINK LTERM MASTER MSNAME NODE PTERM STATUS LINE STATUS LINK STATUS LTERM STATUS MSNAME STATUS NODE STATUS PTERM
External subsystems and connections to external subsystems	CCTL OASN SUBSYS SUBSYS
VTAM	TIMEOVER

For example, to determine whether the database is started, you can use the /DISPLAY DATABASE command after you enter a /START DATABASE command.

Related Reading: For detailed information about the /DISPLAY command, see IMS Version 9: Command Reference.

Monitoring Structures on a Coupling Facility

The following z/OS operator commands are especially useful in monitoring structure activity:

• DISPLAY XCF, STRUCTURE : Used to display the status of structures defined in your active policy.

• DISPLAY XCF, STRUCTURE,STRNAME= : Used to display detailed information about a specific structure. The three structures that are important to IMS are the IRLM, OSAM, VSAM, shared MSGQ, and shared EMHQ structures.

These commands let you look at structures on a coupling facility to determine resource status and, for failures, gather information for problem determination.

Related Reading: For detailed information about these commands, see z/OS MVS System Commands.

Controlling Data Sharing Using DBRC

DBRC allows you to control access to data by IMS subsystems that participate in data sharing. Using DBRC, you can modify, initiate, and delete the current status indicators in the RECON data set to change:

• The access intent of online IMS subsystems

• The share level of registered databases

Your data sharing environment depends on the status of the databases and subsystems as indicated in the RECON data set.

Related Reading: For more information about how DBRC participates in data sharing, see "Supporting Data Sharing" on page 391.

You can modify the share level indicator using a form of one of the DBRC online change commands, /RMCHANGE.