Advanced Topics › Control and Checkpoint File Considerations › How You Migrate to a New Control File

How You Migrate to a New Control File

Control file migration is the process by which CA MIM leaves its current control file and begins using another control file to communicate globally.

Any system in a synchronized MIMplex can initiate migration to an alternate file. Migrations may be initiated by command or because of a recovery situation.

While CA MIM is executing, you can migrate between physical and virtual control files, provided you meet the following criteria:

• At least one physical (DASD or coupling facility list structure) control file is allocated to CA MIM. You can specify ALLOCATE statements in your MIMINIT member, or you can issue the ALLOCATE command dynamically while CA MIM is executing.
• At least one system is master eligible. A master eligible system has XCF or CTC connectivity to every other system in the MIMplex. You can dynamically add CTC devices using the CTCPATH command to complete connectivity while CA MIM executes.

CA MIM may automatically migrate to a new control file as part of error recovery in the following cases:

• If the current control file becomes unusable.
• When migrating from one virtual control file to another in a CTCDASD environment, CA MIM migrates to the DASD control file or coupling facility structure control file for a few seconds while re-synchronization takes place. After synchronization, the virtual control file automatically migrates to the new virtual control file.