Cool but unknown RMAN feature

Unknown to me anyway until just this week.

Some time ago I read a post about RMAN on Oracle-L that detailed what seemed like a very good idea.

The poster's RMAN scripts were written so that the only connection while making backups was a local one using the control file only for the RMAN repository.

rman target sys/manager nocatalog

After the backups were made, a connection was made to the RMAN catalog and a SYNC command was issued.

The reason for this was that if the catalog was unavailable for some reason, the backups would still succeed, which would not be the case with this command:

rman target sys/manager catalog rman/password@rcat

This week I found out this is not true.

Possibly this is news to no one but me, but I'm sharing anyway. :)

Last week I cloned an apps system and created a new OID database on a server. I remembered to do nearly everything, but I did forget to setup TNS so that the catalog database could be found.

After setting up the backups vie NetBackup, the logs showed that there was an error condition, but the backup obviously succeeded:

archive log filename=/u01/oracle/oradata/oiddev/archive/oiddev_arch_1_294_709899427.dbf recid=232 stamp=710999909
deleted archive log
archive log filename=/u01/oracle/oradata/oiddev/archive/oiddev_arch_1_295_709899427.dbf recid=233 stamp=710999910
Deleted 11 objects


Starting backup at 16-FEB-10
released channel: ORA_DISK_1
allocated channel: ORA_SBT_TAPE_1
channel ORA_SBT_TAPE_1: sid=369 devtype=SBT_TAPE
channel ORA_SBT_TAPE_1: VERITAS NetBackup for Oracle - Release 6.0 (2008081305)
channel ORA_SBT_TAPE_1: starting full datafile backupset
channel ORA_SBT_TAPE_1: specifying datafile(s) in backupset
including current controlfile in backupset
channel ORA_SBT_TAPE_1: starting piece 1 at 16-FEB-10
channel ORA_SBT_TAPE_1: finished piece 1 at 16-FEB-10
piece handle=OIDDEV_T20100216_ctl_s73_p1_t711086776 comment=API Version 2.0,MMS Version 5.0.0.0
channel ORA_SBT_TAPE_1: backup set complete, elapsed time: 00:00:45
Finished backup at 16-FEB-10

Starting Control File and SPFILE Autobackup at 16-FEB-10
piece handle=c-3982952863-20100216-02 comment=API Version 2.0,MMS Version 5.0.0.0
Finished Control File and SPFILE Autobackup at 16-FEB-10

RMAN> RMAN>

Recovery Manager complete.

Script /usr/openv/netbackup/scripts/oiddev/oracle_db_rman.sh
==== ended in error on  Tue Feb 16 04:07:59 PST 2010  ====

That seemed rather strange, and it was happening in both of the new databases.
The key to this was to look at the top of the log file, where I found the following:

BACKUP_MODE: lvl_0
BACKUP_TYPE: INCREMENTAL LEVEL=0
ORACLE_SID : oiddev
PWD_SID    : oiddev
ORACLE_HOME: /u01/oracle/oas
PATH: /sbin:/usr/sbin:/bin:/usr/bin:/usr/X11R6/bin

Recovery Manager: Release 10.1.0.5.0 - Production

Copyright (c) 1995, 2004, Oracle.  All rights reserved.


RMAN;
connected to target database: OIDDEV (DBID=3982952863)

RMAN;
RMAN-00571: ===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================
RMAN-04004: error from recovery catalog database: ORA-12154: TNS:could not resolve the connect identifier specified

RMAN;
Starting backup at 16-FEB-10
using target database controlfile instead of recovery catalogallocated channel: ORA_SBT_TAPE_1
channel ORA_SBT_TAPE_1: sid=369 devtype=SBT_TAPE
channel ORA_SBT_TAPE_1: VERITAS NetBackup for Oracle - Release 6.0 (2008081305)
channel ORA_SBT_TAPE_1: starting incremental level 0 datafile backupset

Notice the line near the bottom of the displayed output?

The one that says "using target database controlfile instead of recovery catalog" ?

RMAN will go ahead with the backup of the database even though the connection to the catalog database failed.  This apparently only works when running in a scripted environment, as when I tried connecting on the command line RMAN would simply exit when the connection to the catalog could not be made.

The RMAN scripts are being run on a linux server in the following format:

$OH/bin/rman target sys/manager catalog rman/password@rcat <<-EOF >> $LOGFILE

rman commands go here

EOF

This was quite interesting to discover, and my be old news to many of you, but it was new to me.

This is not exactly a new feature either - one of the databases being backed up is 9.2.0.6. And of course there is now no need to update the backup scripts.