Cloning RAC Database with RMAN fails with error

Steps for cloning a RAC database  with RMAN is similar to cloning a single instance database. But while using rman duplicate in 10g, you will get following errors

RMAN-00571: ===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================
RMAN-03002: failure of Duplicate Db command at 06/14/2010 00:09:42
RMAN-03015: error occurred in stored script Memory Script
RMAN-06136: ORACLE error from auxiliary database: ORA-38856: cannot mark instance UNNAMED_INSTANCE_2 (redo thread 2) as enabled

RMAN> exit

This is due to Bug 4355382 ORA-38856: FAILED TO OPEN DATABASE WITH RESETLOGS WHEN USING RAC BACKUP

To avoid this we need to set the following initialization parameter on the auxiliary database; and restart the database in no mount mode

_no_recovery_through_resetlogs=TRUE

Unset this once rman duplicate command completes successfully. One more notable thing which I noticed while cloning this database was that if you use skip readonly clause to skip duplicating read only tablespace, entries for read only tablespace still remain and file names are marked as missing

/oracle/product/10.2/dbs/MISSING00048
OFFLINE READ ONLY

/oracle/product/10.2/dbs/MISSING00049
OFFLINE READ ONLY

This is normal behavior and not a bug. From docs

SKIP READONLY Excludes datafiles in read-only tablespaces from the duplicate database.
Note: A record for the skipped read-only tablespace still appears in DBA_TABLESPACES. By using this feature, you can activate the read-only tablespace later. For example, you can store the read-only tablespace data on a CD-ROM, then mount the CD-ROM later and view the data

If you don’t plan to make use of these tablespaces, you can drop them by simply using drop tablespace command .Meanwhile do you know that  tables can be dropped from read-only tablespace. To know more about it, you can read this entry from Tanel describing this behavior

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