ORA-38856

RMAN Duplicate from RAC backup fails ORA-38856 [ID 334899.1]

Applies to:

Oracle Server - Enterprise Edition - Version: 10.2.0.1 and later   [Release: 10.2 and later ]
Information in this document applies to any platform.

Symptoms

RMAN duplicate using a backup taken from a RAC installation fails on opening the clone instance with
RMAN-06136: ORACLE error from auxiliary database:

ORA-38856: cannot mark instance UNNAMED_INSTANCE_2 (redo thread 2) as enabled
The target database is a RAC two node database being duplicated to a single instance database.

Changes

RMAN is being used to clone from a source backup  taken from a RAC database.

Cause

Unpulbished Bug 4355382 ORA-38856: FAILED TO OPEN DATABASE WITH RESETLOGS WHEN USING RAC BACKUP
ORA-38856 is the expected error during open database resetlogs when the set of enabled instances (redo threads) in the controlfile does not match the set of enabled instances (redo threads) in datafile checkpoint. This is expected behavior in a normal RAC restore/recover/open resetlogs situation.
However, in a cloning scenario where, once the clone database is opened with resetlogs you would never expect to restore the old (RAC) backup , this check doesnt matter.

Solution

As a workaround you could do the following:

1.Set the following parameter in the auxiliary init.ora file:

_no_recovery_through_resetlogs=TRUE

Then open with resetlogs;
Once the auxiliary has opened, removed this hidden parameter.