Patent ID: 7036044

Claim:
In a computer system comprising a processor and one or more physical storage media, wherein the computer system also includes a log with a plurality of log entries, wherein a log entry may be a redo log entry, which includes redo data for recreating an operation the was performed on the content of an object, or a log entry may be an undo log entry, which references undo data necessary to reverse an effect of an operation that was performed on the contents of an object, wherein a reference to undo data can be a reference to a location at an auxiliary storage, a method for determining appropriate undo data to associate with a particular object during a roll-forward recovery so as to cause the auxiliary storage to be consistent with the log, the method comprising: an act of identifying that a redo log entry includes redo data associated with an operation that was performed on the contents of the particular object; an act of identifying the location of appropriate undo data that is necessary to reverse an effect of the operation associated with the redo data; and if the location of the appropriate undo data is in the particular object, and performing the operation associated with the redo data would result in potential loss of the appropriate undo data from the particular object, an act of copying the appropriate undo data from the particular object to a location referenced in an undo log entry that corresponds the redo log entry.