Explain the Log Based Recovery Method?
The system log that is generally written on stable storage consists of the redundant data required to recover from volatile storage failures and as well from errors discovered by the transaction or the database system. System log is as well known as log and has sometimes been known as the DBMS journal. In case of system crash the log is processed from the starting to the point where system crashes. Every transaction, those have been recorded their-of-transaction marker, will be committed if not rolled back. The simplicity and very easy to use the main benefits of this method.
The drawback are:
(A) Inefficient for the application, which have large volume of information,
(b) In case of system crash along with loss of volatile information, the log information collected in buffers will as well be lost and transaction that had been completed for some period prior to the system crash might be missing their relevant end-of-transaction markers in the log; if such transactions are rolled back then similarly to be partially undone.