How to perform a clone from active database

With Oracle 11g, a new method to clone databases was introduced: "Clone from Active Database".
This method allows for cloning of a database using RMAN's DUPLICATE command, but without being dependent on any previous backups being available.

The following are my notes on how to use this feature to produce a clone from production database PRODDB01 to test database TESTDB01.

In file run_duplication.cmd:

connect catalog cataloguser/password@RMANCAT
connect target sys/clonedb@PRODDB01
connect auxiliary sys/clonedb@TESTDB01;
allocate channel c1 type disk;
allocate channel c2 type disk;
allocate auxiliary channel aux1 type disk;
allocate auxiliary channel aux2 type disk;
configure device type disk parallelism 2;
run {
debug io;
DUPLICATE TARGET DATABASE TO TESTDB01
FROM ACTIVE DATABASE
SKIP TABLESPACE TOOLS;
debug off;
}
exit

to execute:

rman cmdfile='run_duplication.cmd' debug trace='run_duplication.trc' log='run_duplication.log'


For this to work smoothly I followed the principles below:

• Script executed from the target server
• Auxiliary database must be in NOMOUNT mode
• Sys passwords must be identical on both source and target.
• Use the notation uid/pwd@<ORACLE_SID> when you Connect to both target and auxiliary. Do not use operating system authenticaion ( connect / ) - it will throw an error
• The db_block_size parameter must be identical on both source and target
• TNS connection must exist on both sides e.g. communication must be able to go from and from the source and the target. If not you will see the error

RMAN-03002: failure of Duplicate Db command at 07/21/2015 10:06:15
RMAN-05501: aborting duplication of target database
RMAN-03015: error occurred in stored script Memory Script
RMAN-03009: failure of backup command on c1 channel at 07/21/2015 10:06:15
ORA-17629: Cannot connect to the remote database server
ORA-17627: ORA-12154: TNS:could not resolve the connect identifier specified
ORA-17629: Cannot connect to the remote database server

• I set the db_file_name_convert and the log_file_name_convert parameter in the auxiliary database. Make sure you check the location of the tempfiles, too, and include this in the db_file_name_convert value.
• I had no success using the TABLESPACE clause (which means an implicit EXCLUDE of all other tablespaces except those named explicitly)
• Using SKIP TABLESPACE ,, etc works, if the tablespaces are self-contained, meaning there are no referential constraints from object in one tablespace to another (even if both are skipped!)

Remember to reregister the duplicated database if it's backed up using a catalog database:

RMAN> connect target /
RMAN> list incarnation of database;
RMAN> register database;
RMAN> list incarnation of database;


The prerequisites for ACTIVE DATABASE cloning as laid out in the Oracle documentation are:

• At least one normal target channel and at least one AUXILIARY channel are required.
• When you connect RMAN to the source database as TARGET, you must specify a password, even if RMAN uses operating system authentication.
• The source database must be mounted or open. If the source database is open, then archiving must be enabled.
• If the source database is not open, then it must have been shut down consistently.
• When you connect RMAN to the auxiliary instance, you must provide a net service name. This requirement applies even if the auxiliary instance is on the local host.
• The source database and auxiliary instances must use the same SYSDBA password, which means that both instances must have password files.
• You cannot use the UNTIL clause when performing active database duplication. RMAN chooses a time based on when the online data files have been completely copied, so that the data files can be recovered to a consistent point in time.