Re: Migration R12.1.3 to new server

Posted by ErmanArslansOracleBlog on Sep 26, 2022; 7:17am
URL: http://erman-arslan-s-oracle-forum.124.s1.nabble.com/Migration-R12-1-3-to-new-server-tp11083p11097.html

RESETLOGS is required after incomplete recovery.
It depends on the migration method, and the capabilities you have.

For instance; RMAN Duplicate uses OPEN RESETLOGS, as it is the way it works;

When running an RMAN duplicate in Oracle 11.2 and higher, RMAN will perform the following steps:

1. It restores a controlfile from the target into the auxiliary
2. It resets the db_name to the target so the controlfile can be mounted.
3. It restores the datafiles setting the auxiliary datafiles in the proper location using either db_file_name_convert or 'set newname', if specified.
4. It recovers the auxiliary datafiles to the 'until' clause specified or derived.
5. It recreates the controlfile with the system datafile (datafile #1)
6. It catalogs the auxiliary datafiles into the newly created datafiles.
7. Executes a 'switch datafile to copy' of all the datafiles.
8. It changes the DBID and opens the database with resetlogs.

See?

For RMAN , we have following document for instance as well ->

How to clone the database using RMAN without new incarnation (with NORESETLOGS) (Doc ID 1608236.1)

Basically, if you do an incomplete recovery , then you have to open your database with resetlogs option.
The incomplete recovery is -> restore a backup, apply some redo (not whole) and recover the database according to the redo that you apply, to a specific time or SCN.

At the recovery process, we should apply the online redo logs when the time comes, but if we didn't apply them, or if the recovery process applies them as archived redo logs (when we use backup controlfile, recovery process treats redologs as archived redologs), then we need to reset our redologs and that's why we have to use resetlogs option.

By using a backup controlfile, you actually saying, my control file is a backup controlfile:)
In the following 2 conditions , you use it;

1)If the controlfile is older than any of your datafiles.
2)You do not have a valid current control file to use.

And those mechanisms like RMAN duplicate use backup controlfile for one of these reasons.