Databases Reference
In-Depth Information
Using the FRA for Archive Log Files
The FRA is an area on disk—specified via database initialization parameters—that can be used to store files, such as
archive redo logs, RMAN backup files, flashback logs, and multiplexed control files and online redo logs. To enable the
use of a FRA, you must set two initialization parameters (in this order):
DB_RECOVERY_FILE_DEST_SIZE
specifies the maximum space to be used for all files that are
stored in the FRA for a database.
•
DB_RECOVERY_FILE_DEST
specifies the base directory for the FRA.
•
When you create a FRA, you're not really creating anything—you're telling Oracle which directory to use when
storing files that go in the FRA. For example, say 200GB of space are reserved on a mount point, and you want the base
directory for the FRA to be
/u01/fra
. To enable the FRA, first set
DB_RECOVERY_FILE_DEST_SIZE
:
SQL> alter system set db_recovery_file_dest_size=200g scope=both;
Next, set the
DB_RECOVERY_FILE_DEST
parameter:
SQL> alter system set db_recovery_file_dest='/u01/fra' scope=both;
If you're using an
init.ora
file, modify it with an OS utility (such as
vi
) with the appropriate entries.
After you enable a FRA, by default, Oracle writes archive redo logs to subdirectories in the FRA.
■
if you've set the
LOG_ARCHIVE_DEST_N
parameter to be a location on disk, archive redo logs aren't written
to the Fra.
Note
You can verify that the archive location is using a FRA:
SQL> archive log list;
If archive files are being written to the FRA, you should see output like this:
Database log mode Archive Mode
Automatic archival Enabled
Archive destination USE_DB_RECOVERY_FILE_DEST
You can display the directory associated with the FRA like this:
SQL> show parameter db_recovery_file_dest
When you first implement a FRA, there are no subdirectories beneath the base FRA directory (specified with
DB_RECOVERY_FILE_DEST
). The first time Oracle needs to write a file to the FRA, it creates any required directories
beneath the base directory. For example, after you implement a FRA, if archiving for your database is enabled, then
the first time a log switch occurs, Oracle creates the following directories beneath the base FRA directory:
<SID>/archivelog/<YYYY_MM_DD>
Each day that archive redo logs are generated results in a new directory's being created in the FRA, using the
directory name format
YYYY_MM_DD
. Archive redo logs written to the FRA use the OMF format naming convention
(regardless of whether you've set the
LOG_ARCHIVE_FORMAT
parameter).
