Oracle Recovery

CKPT is an Oracle backgroud process that timestamps all datafiles and control files to indicate that a checkpoint has occurred. It signals DBWn to write blocks to disk.

Online Redo Log records changes to the database as they occur. it enable Oracle database to recover committed data not yet written to the data file. the contents of the log include uncommitted transaction, undo data, and schema and object management statements.

Archived Redo Log is a coping of filled groups of redo log files on offline destinations. The archived redo log contains a copy of every group created since archivelog mode enabled. The archive log files can be used to recover database from last backup to current failure point.