Recovery and restart in interconnected systems

This section describes those aspects of CICS® recovery and restart that apply particularly in the intercommunication environment. It assumes that you are familiar with the concepts of units of work (UOWs), synchronization points (syncpoints), dynamic transaction backout, and other topics related to recovery and restart in a single CICS system. These topics are presented in detail in the CICS Recovery and Restart Guide.

In the intercommunication environment, most of the single-system concepts remain unchanged. Each system has its own system log (or the equivalent for non-CICS systems), and is normally capable of either committing or backing out changes that it makes to its own recoverable resources.

In the intercommunication environment, however, a unit of work can include actions that are to be taken by two or more connected systems. Such a unit of work is known as a distributed unit of work, because the resources to be accessed are distributed across more than one system. A distributed unit of work is made up of two or more local units of work, each of which represents the work to be done on one of the participating systems. In a distributed unit of work, the participating systems must agree to commit the changes they have made; this, in turn, means that they must exchange syncpoint requests and responses over the intersystem sessions. This requirement represents the single major difference between recovery in single and multiple systems.

The rest of this section contains the following topics:

[[ Contents Previous Page | Next Page Index ]]