Rman backup of physical standby

Question

Hi:
I am on 10.2.0.3.
Trying to run rman backup on physical standby while it's in managed recovery mode. Whould it be useable for recovery being that it will be inconsistent?
I went through this: http://youngcow.net/doc/oracle10g/server.102/b14239/rman.htm and some other sites
but they don't tell how to register the standby first. By the way, do I have to change DBID as well? Am I missing some step?
Below are the errors I'm getting.
TIA.
RMAN> register database;
RMAN-00571: ===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================
RMAN-03002: failure of register command at 12/04/2008 11:42:02
RMAN-08040: full resync skipped, control file is not current or backup
RMAN> show all;
RMAN configuration parameters are:
RMAN-00571: ===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================
RMAN-03002: failure of show command at 12/04/2008 11:42:09
RMAN-06004: ORACLE error from recovery catalog database: RMAN-20001: target database not found in recovery catalog

Answer 1

I meant this sentence from the documentation:
In a standby environment, backing up data files and archived redo log files taken on the primary or standby system are usable on either system for recovery.
You can take a backup (datafiles and archivelogs) on the primary side and then restore/recover on the standby side. The same is true vice versa. There's no difference,where you take the backup. The recovery catalog is necessary to resync the controlfiles on both sides with the backup records. By the way I prefer in any case to take archivelog backups on the primary side. Because sometimes archivelog transfer to the standby is interrupted and you don't catch all archivelogs on the standby side (in the moment you take the backup).
Werner