Operating Systems: Concurrent and Distributed Software Design

21.5. Use of a recovery log

As noted in Section 21.1, it is assumed that a daily dump of the system's persistent state is taken and that the DBMS must make a record of subsequent activity if complete crash resilience is to be achieved at any time.

An outline of the general approach is that, on an invocation, the object value is updated in persistent store and a record of the invocation is made in a log. We have already assumed that every object keeps information (for concurrency control purposes) of the kind we require to be logged and we can require objects to write log records. In order to achieve a recoverable state we must consider when the update to persistent object state is made and when the corresponding log record is written to persistent ...