use the following formula to estimate the disk quota, 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:
Disk Quota =
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)
To determine the optimum size for the fast recovery area:
1. If you plan to use flashback logging or guaranteed restore points, then query
V$ARCHIVED_LOG to determine how much redo the database generates in the
time to which you intend to set DB_FLASHBACK_RETENTION_TARGET.
If flashback logging is enabled, then run the database under a normal workload
for the time period specified by DB_FLASHBACK_RETENTION_TARGET.
In this way, the database can generate a representative sample of flashback logs.
Query the V$FLASHBACK_DATABASE_LOG view as follows:
The result is an estimate of the disk space needed to meet the current flashback
retention target, based on the database workload since Flashback Database was
Oracle recommends that DB_RECOVERY_FILE_DEST be set to a different value from
DB_CREATE_FILE_DEST or any of the DB_CREATE_ONLINE_LOG_DEST_n