In this section, we??™ll review several different
aspects of RMAN recovery operations.
RMAN can perform restore and recovery operations at various levels of granularity, and most
of these operations can be performed while the database is open and available to users. We can
recover individual blocks, tablespaces, datafiles, or even an entire database. In addition, RMAN
has various methods of validating a restore operation without performing an actual recovery on
the database datafiles.
Block Media Recovery
When there are only a small handful of blocks to recover in a database, RMAN can perform block
media recovery rather than a full datafile recovery. Block media recovery minimizes redo log
application time, and it drastically reduces the amount of I/O required to recover only the block
or blocks in question. While block media recovery is in progress, the affected datafiles can remain
online and available to users.
NOTE
Block media recovery is only available from within the RMAN
application.
There are a number of ways in which block corruption is detected. During a read or write
operation from an insert or select statement, Oracle may detect a block is corrupt, write an error
in a user trace file, and abort the transaction. An RMAN backup or backup validate command can
record corrupted blocks in the dynamic performance view V$DATABASE_BLOCK_CORRUPTION.
In addition, the SQL commands analyze table and analyze index could uncover corrupted blocks.
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