Restoring the Control File - RMAN Recipes for Oracle Database 12c - page 297

RMAN will now display output similar to the following:

channel ORA_DISK_1: AUTOBACKUP found: c-3412777350-20120717-07
channel ORA_DISK_1: restoring control file from AUTOBACKUP
c-3412777350-20120717-07

When you set the DBID, you are instructing RMAN to search outside the fast recovery area in the default location
for a backup file that was formatted with the %F parameter.

■ Note See Table 10-1 for details about the %F format variable.

RMAN will look in the default location for the RMAN backup piece file. The default location varies by operating
system. On Linux/Unix, the default location is ORACLE_HOME/dbs. On Windows installations it's usually ORACLE_
HOME\database.
RMAN will start with today's date and look for a control file backup with today's date as part of the backup file
name. If RMAN doesn't find a backup piece with today's date as part of the file name, it will then look in the default
location for a file name with yesterday's date included as part of the name, and so forth.
By default, RMAN will attempt to retrieve from auto backups created within the past seven days only. If you want
to modify the default behavior, use the maxdays parameter. This example instructs RMAN to look for a control file
backup created in the past 20 days:

RMAN> connect target /
RMAN> startup nomount;
RMAN> set dbid 3412777350;
RMAN> restore controlfile from autobackup maxdays 20;

You can also instruct RMAN to search for control file backups by sequence number via the maxseq parameter. The
sequence number used is defined by the %F format variable and is generated when the control file backup is created.
This next example instructs RMAN to look for a control file backup file that has a sequence number of 10 or less:

RMAN> connect target /
RMAN> startup nomount;
RMAN> set dbid 3412777350;
RMAN> restore controlfile from autobackup maxseq 10;

■ The maxdays and maxseq parameters are useful only when your control file backup file names are formatted with
the %F format mask. The %F format mask embeds a date and a sequence number in the backup piece name.

Note

Using Auto Backup, with RMAN Backup Piece in a Nondefault Location
If you used the configure controlfile autobackup format command to specify the location of the control file
backup to a nondefault location, then you have to tell RMAN where to find the backup file. For example, say you
configured your auto backup of the control file like this:

RMAN> configure controlfile autobackup format for device type disk
to '/u01/rman/o12c/%F';