Database Reference
In-Depth Information
starting Oracle instance without parameter file for retrieval of spfile
Oracle instance started
Total System Global Area 1068937216 bytes
Fixed Size 2296576 bytes
Variable Size 281019648 bytes
Database Buffers 780140544 bytes
Redo Buffers 5480448 bytes
RMAN> run {
2> allocate channel c1 device type disk;
3> restore spfile;
4> }
allocated channel: c1
channel c1: SID=11 device type=DISK
Starting restore at 22.09.2013 21:01
channel c1: starting datafile backup set restore
channel c1: restoring SPFILE
output file name=/u01/app/oracle/product/12.1.0.1/dbhome_1/dbs/spfileCDB1.ora
channel c1: reading from backup piece
+RECO/CDB1/AUTOBACKUP/2013_09_22/s_826832795.297.826832795
channel c1: piece handle=+RECO/CDB1/AUTOBACKUP/2013_09_22/s_826832795.297.826832795
tag=TAG20130922T194635
channel c1: restored backup piece 1
channel c1: restore complete, elapsed time: 00:00:05
Finished restore at 22.09.2013 21:01
released channel: c1
RMAN>
It does not get any easier than that. Should you be lucky enough to be on a database server with lots of CPUs
then you might get an ORA-4031 error during the restore or channel allocation. In this case you have to create a
minimalistic parameter file with a sufficiently sized SGA before starting the database as shown previously.
Restoring the control file
The loss of the controlfile(s) is an intrusive event, and unfortunate since a lot of useful information is contained
in it. Thankfully the loss of a controlfile is no longer such a tragedy as it was in the 9i days thanks to the “catalog”
command which has been introduced in Oracle 10g. It allows you to search directories for backups which are then
cataloged in the controlfile, and therefore made available again for restore operations. The restore of the control file
will still require you to open the database with the resetlogs option though! You may want to take a backup after the
command completed.
Another great feature of recent Oracle versions is that the restore of the controlfile does not require editing the
parameter or server parameter file anymore when using Oracle Managed Files. In older releases Oracle complained that
it could not restore a controlfile with an OMF name. Instead, one had created a parameter file from the spfile, edit the
parameter file (remove the *.control_files entry) and create a spfile from the pfile before starting the instance. These days
are long over, and changes to the initialization parameters related to the control files are not normally necessary.
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