Techniques are described herein for returning a repository to a prior state. The repository may be, for example a database, and the prior state may be, for example the consistent state that the database had at a particular point in time in the past. When a operator-caused error has been introduced to the database by changes made by an already-committed transaction, the techniques described herein may be used to recover from the error by returning the database to a point in time prior to the commit time of the transaction that introduced the error. The techniques involve the generation of "physical undo" information, and the use of the physical undo information in conjunction with physiological undo and physiological redo to efficiently return a repository to the prior state.
Provided is a computer system including a first storage subsystem and a second storage subsystem. The first storage subsystem has a first storage unit and a first control unit. The second storage subsystem has a second storage unit and a second control unit. The first control unit records journals, and identifies, when data stored in the first storage unit is to be migrated to the second storage unit, which ones of the recorded journals are related to the data that is to be migrated. The first control unit chooses the identified journals one at a time in reverse chronological order, and judges whether or not the chosen journal corresponds to a data update made at some point between a current time and a time that precedes the current time by a length of a journal retention term set for the second storage subsystem.
A system, method, apparatus, means and computer program code for processing a request to create a snapshot version of a database are provided which include identifying a current state of a converter table, the converter table including information identifying a plurality of page identifiers and a physical location of each of the page identifiers in a data area, saving the current state of the converter table, and marking each of the plurality of page identifiers to prevent overwriting.
Disclosed is a method to synchronize the state of an application and an application's objects with data stored on the storage system. The storage system provides API's to create special data, called a marker journal, and stores it on a journal volume. The marker contains application information, e.g. file name, operation on the file, timestamp, etc. Since the journal volume contains markers as well as any changed data in the chronological order, IO activities to the storage system and application activities can be synchronized.
