1.

Why More Redo Is Generated During Hot Backup?

Answer»

During the HOT backup, when a TABLESPACE is put up in the backup mode, all the datafiles that belongs to the tablespace get their checkpoint frozen.
When DBWR process writes the changed data BLOCKS to the datafile, the same data blocks are written to redo log files to support roll forward process to MAINTAIN the consistency of a hot backup. This is the reason for large redo generation and requirement of archive logs for hot backup.

During the hot backup, when a tablespace is put up in the backup mode, all the datafiles that belongs to the tablespace get their checkpoint frozen.
When DBWR process writes the changed data blocks to the datafile, the same data blocks are written to redo log files to support roll forward process to maintain the consistency of a hot backup. This is the reason for large redo generation and requirement of archive logs for hot backup.


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