6.3. Some definitions
If you are interested in DFSMStvs as a storage administrator, you may not be familiar with some of the terms and concepts that will be used throughout this book. This section offers some brief definitions.
6.3.1. Backward recovery
If a transaction fails, it may leave data in an inconsistent state. Perhaps one update has been requested, but the program failed before requesting a related update.
The process of removing changes which are possibly inconsistent is variously called backward recovery, rollback, or backout. It requires the use of a log that holds images of the records before they were updated. This log is called an undo log. In CICS terminology, the records are known as before images.