Transactional recovery is the capability to isolate the changes made to recoverable resources by a transaction. This means that when the transaction makes a change, that change is seen only by that transaction. After the transaction reaches the commit point, all changes that the transaction made are visible to other transactions. If an application decides to back out a transaction rather than complete it, then the resource manager backs out all changes that the transaction made. This transactional recovery is a major part of transaction processing.

For example, consider a context in which changes are made to two different records in a recoverable VSAM data set. A field in one record is decremented from 200 to 100. A field in the other record item is incremented from 700 to 800. Transactional recovery ensures that either both changes are made or neither change is made. When the application requests that the changes be committed, both changes are made atomically.

If an application makes these changes to nonrecoverable data and the application or the system fails, one or both of the changes could be lost.