A virtual control file (VCF) is an area of virtual storage that is located in a pre-selected CA MIM address space. The CA MIM address space that is selected to manage the VCF is known as the master system. A system is master eligible if it has connectivity to all systems participating in the MIMplex.
When client systems must propagate global information, they must request the VCF through one of these methods:
Once the master system receives the request, it transports the VCF back to the requesting client system. Only the master system knows which system has the VCF at any given moment. Once the client system receives the VCF, it is updated and transported back to the master. The master system then sends the VCF to the next waiting requestor (client system). The master system services VCF access requests on a first in, first out (FIFO) basis. This philosophy ensures that the systems with the most global activity receive the best possible service.
In a VCF environment, CA MIM supports a simultaneous mix of CTC devices and XCF for MIMplex communications. CA MIM systems within a sysplex can use XCF communication, while systems outside the sysplex must use CTC devices.
Use the VCFPREFERENCE command to dictate what type of communication path a client system should use when requesting the control file from the master system. If only one type of path is available (XCF or CTC device), then it is used regardless of your preference setting. In addition, the ability to use both XCF and CTC devices can be useful in recovery situations. This ability lets CA MIM fall back to any communication path that is available, if the current path is in error. Define the CTC devices to CA MIM using either of the following methods:
CA MIM automatically discovers the XCF paths during initialization and as systems join the CA MIM XCF group.
|
Copyright © 2014 CA.
All rights reserved.
|
|