RE: controlfile recovery

Dennis,

There is a procedure within the standard Oracle 8i documentation that shows you how to recover the control file from a backup peice. I've included the procedure below. When recovering the database without a backup catalog, the trick is to ensure that the controlfile is the LAST thing that is backed up. The last backup command "backup current controlfile" ensures that it is possible to recover all the archive logs backed up in the previous command. That is, the control contains the details about the archive log backup (note, the "...include current controlfile" does not contain details about the archive log backup).

run
{

        #
        # Perform a full, complete, hot backup of the database
        # followed by a backup of the archived logs.
        # We backup the controlfile as the last step to allow
        # us to recover the last archived log if we ever have
        # to recover the database without a recovery catalog.
        #
        allocate channel t1 type 'sbt_tape' format '%d_%U';

        backup ( database include current controlfile );
        sql 'alter system archive log current';
        backup ( archivelog all delete input );
        backup current controlfile;

        release channel t1;

The PL/SQL block that I use to recover the controlfile is below. You need to know the name of the backup peice that contains the controlfile backup to use it.

DECLARE
  devtype varchar2(256);
  done boolean;
BEGIN
  --devtype := dbms_backup_restore.deviceallocate('devtype', params=>'');   devtype := dbms_backup_restore.deviceallocate('sbt_tape', params=>'');

• Replace 'devtype' with the device type you used when creating the backup:
• NULL or sbt_tape. If you used an sbt_tape device and specified a 'parms'
• option on the RMAN allocate channel command, then put that parms data in
• the 'params' operand here.

  dbms_backup_restore.restoresetdatafile;

  dbms_backup_restore.restorecontrolfileto('/tmp/control01.ctl');

• This path specifies the location for the restored control file. If there
• are multiple control files specified in the init.ora file, copy the
• control file to all specified locations before mounting the database.

  dbms_backup_restore.restorebackuppiece('/SID_5ge4ps5m_1_1',done=>done);

• Replace 'SID_5ge4ps5m_1_1' with the your backup piece handle. This example assumes
• that the backup set contains only one backup piece. If there is more than
• one backup piece in the backup set (which only happens if the RMAN command
• set limit kbytes is used), then repeat the restorebackuppiece statement
• for each backup piece in the backup set.

END;
/

Cheers,
Craig.

-----Original Message-----
Sent: Saturday, 26 April 2003 8:22 AM
To: Multiple recipients of list ORACLE-L

AK - Congratulations on getting Robert's book. This issue of recovering the controlfile depends somewhat on which Oracle version you are using. I think this is easier in Oracle 9i. I started working on Oracle 8i recovery before Robert's book was available. I was not able to recover the controlfile from the RMAN backup. I found it easier to ALTER DATABASE BACKUP CONTROLFILE TO 'XXX'; after the RMAN backup. I included that in my RMAN script and have been able to recover databases on another server.

Dennis Williams
DBA, 40%OCP, 100% DBA
Lifetouch, Inc.
dwilliams_at_lifetouch.com

-----Original Message-----
Sent: Friday, April 25, 2003 4:32 PM
To: Multiple recipients of list ORACLE-L

Can you reply to this before heading to IOUG .  

I am testing restoration controlfile from RMAN backup . with nocatalog option .  

Is there any way you can recover controlfile if database is not mounted .  

I used dbms_backup_recovery package as described in Robert's book . But looks like lost somewhere because after restoring control file database complains system01.dbf is from past backup . Logically seems okay , scn in control file might be different then what is in datafile header . But now what ?
I try to recover database and it is saying recovery using backup controlfile must be done.  

I am lost . any I idea what I am doing wrong here .  

thanks,
-ak

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