Tuning Recovery - Expert Oracle RAC Performance Diagnostics and Tuning - page 331

this location. The recovery area should be able to contain a copy of all datafiles in the database and the incremental
backups per the backup strategy. Oracle has provided a formula to calculate space required for FRA location:

space required = size of a copy of database + size of an incremental backup
+ size of (n + 1) days of archived redo logs
+ size of (y + 1) days of foreign archived redo logs
(for logical standby) + size of control file +
size of an online redo log member × number of log groups
+ size of flashback logs (based on
DB_FLASHBACK_RETENTION_TARGET value),

where n is the interval in days between incremental updates, and y is the delay in applying the foreign archived redo
logs on a logical standby database.
Once the size is determined, the physical configuration of the FRA could be initiated. Assuming that the database
is already configured for archiving, and the database is currently in ARCHIVELOG mode, the first step to this process is to
connect to the target database using RMAN:

1. Specify the size of the FRA using the following command:

ALTER SYSTEM SET DB_RECOVERY_FILE_DEST_SIZE = <> SCOPE = SPFILE;

2. Specify the location of the FRA using the following command:

ALTER SYSTEM SET DB_RECOVERY_FILE_DEST ='+SSKY_FRA' SCOPE = SPFILE;

The preceding steps will configure the FRA, and the area will be managed by RMAN
during its routine backup operations based on predefined retention policies. It's important
that the destination file location specified by the parameter is on shared storage.
Configuring this area to reside on ASM storage provides good performance benefits.

3. FRA is automatically managed for space utilization based on the retention policies defined

in RMAN. The space utilization could be verified using the following scripts:

14:04:01 SQL> SELECT * FROM V$RECOVERY_FILE_DEST;

NAME SPACE_LIMIT SPACE_USED SPACE_RECLAIMABLE NUMBER_OF_FILES CON_ID
-------------------------------- ----------- ---------- ----------------- --------------- ----------
+SSKY_FRA 5368709120 235929600 0 117 0

Elapsed: 00:00:02.23
14:04:13 SQL> SELECT * FROM V$FLASH_RECOVERY_AREA_USAGE;

FILE_TYPE PERCENT_SPACE_USED PERCENT_SPACE_RECLAIMABLE NUMBER_OF_FILES CON_ID
----------------------- ------------------ ------------------------- --------------- ----------
CONTROL FILE .37 0 1 0
REDO LOG 3.98 0 4 0
ARCHIVED LOG 4.05 2.01 28 0
BACKUP PIECE 3.94 3.86 8 0
IMAGE COPY 15.94 10.43 76 0
FLASHBACK LOG 0 0 0 0
FOREIGN ARCHIVED LOG 0 0 0 0
AUXILIARY DATAFILE COPY 0 0 0 0

8 rows selected.