Database Reference
In-Depth Information
The default retention setting in RMAN is a redundancy retention policy of one copy.
If an FRA is configured, the backup will be removed when space is needed. If an FRA
is not used, you will need to use the RMAN command
DELETE OBSOLETE
(discussed in
Chapter 8, “Understanding Flashback Technology”) to remove the backup metadata and
physical files.
ReCOveRY WiNDOW ReTeNTiON POliCY
The recovery retention policy provides the ability to define a recovery window to be applied
to your backups in a period of days. For example, if you want to be sure you can restore
your database to where it was 14 days ago, you would establish a recovery retention policy
of 14 days and earlier. Note that this setting does not impact the lifetime of a specific backup
based on when the backup occurred but rather ensures that all backups that are retained can
be restored based on the retention policy. This means that backups taken 15, 16, or 30 days
ago may remain valid backups, as demonstrated here and in Figure 3.1:
FiGURe 3.1
Recovery-window retention-policy example: 14 days
Day
1
2
3
4
5
6
7
Full
Backup
Taken
Arch
Backup
Arch
Backup
Arch
Backup
Arch
Backup
Arch
Backup
Arch
Backup
Day
8
9
10
11
12
13
14
Arch
Backup
Arch
Backup
Arch
Backup
Arch
Backup
Arch
Backup
Arch
Backup
Arch
Backup
Day
15
16
17
18
19
20
21
No
Backup
Full
Backup
Taken
Arch
Backup
Arch
Backup
Arch
Backup
Arch
Backup
Arch
Backup
(Still need day 1 backup to restore to day 15; day 1 backup is still valid.)
Day
22
23
24
25
26
27
28
29
30
No
Backup
Full
Backup
Taken
Arch
Backup
Arch
Backup
Arch
Backup
Arch
Backup
Arch
Backup
Arch
Backup
Backup on
Day 1
No Longer
Needed
Your database retention policy is 14 days.
■
You perform a full database backup 1 on day 1; it is of course valid.
■
Archive log backups are taken on days 1 through 14. Backup 1 is now 15 days old. It
remains valid because it is needed to restore the database to days 0 through 14.
■
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