When You Share Data with Another System through CTCAs

Many installations run more than one system on more than one processor complex. In these installations, the systems can be loosely coupled through channel-to-channel adapters (CTCAs). If this is true at your installation, you should make sure you know how to shut down data transmission safely before you remove CTCAs from z/VM®.

If your installation uses CTCAs to connect z/VM or the production system to a network, you must be careful when you switch a CTCA from one virtual machine to another. You must also be careful when you remove the CTCA from z/VM's control (when you vary it offline) or when you shut down the system.

Normally, being careful means you must make sure that other systems have stopped sending data over the CTCA. Before you detach a CTCA or vary it offline, or enter the SHUTDOWN command, contact the operators of the other systems and follow your installation's normal procedures.