The
flash recovery area is a space that is set aside on the disk to contain
archived logs, backups, flashback logs, mirrored control files, and mirrored
redo logs. A flash recovery area simplifies backup storage management and is
strongly recommended. You should place the flash recovery area on a disk that
is separate from the working set of database files. Otherwise, the disk becomes
a single point of failure for your database.
The
amount of disk space to allocate for the flash recovery area depends on the
size and activity levels of your database. As a general rule, the larger the
flash recovery area, the more useful it is. Ideally, the flash recovery area
should be large enough for copies of your data and control files and for
flashback, online redo, and archived logs needed to recover the database with
the backups kept based on the retention policy. (In short, the flash recovery
area should be at least twice the size of the database so that it can hold one
backup and several archived logs.)
Space
management in the flash recovery area is governed by a backup retention policy.
A retention policy determines when files are obsolete, which means that they
are no longer needed to meet your data recovery objectives. The Oracle database
automatically manages this storage by deleting files that are no longer needed.
