Re: Compatibility, Record level issues in 'RMAN duplicate target database'?

qazmlp wrote:
> My requirement is to duplicate the database from Machine-1 into
> Machine-2. Using RMAN utility seems to be a way to go.
>
> Before start using it, I would like to know about how exactly the
> 'RMAN' utility works for 'duplicate target database' command for each
> of the following scenarios?
> 1) There is already a Database existing in Machine-2 with all the
> user Tables empty. The DB schema in Machine-1 & Machine-2 are fully
> compatible.
> 2) There is already a Database existing in Machine-2 with all the
> user Tables empty. The DB schema in Machine-1 & Machine-2 are _not_
> compatible.
> 3) There is already a Database existing in Machine-2 with user Tables
> filled with some records. The DB schema in Machine-1 & Machine-2 are
> fully compatible.
>
> What will be the result of 'RMAN duplicate target database' command in
> such scenarios?
>
> Thanks!

Hi,

You have not mentioned which version of Oracle you are working with so I'll assume 9iR2 (and before) and not 10g.

The short answer is that in all cases the RMAN duplicate will completely   -REPLACE- the database on Machine-2 so the results of all your scenarios above will be the same.

The general requirement for a duplicate on Machine-2 is that you have a compatible Oracle Home and at least a bare bones init.ora, sqlnet access to it and it must be started up NOMOUNT.

The slightly longer answer is that you can create a duplicate on Machine-2 base one a earlier version of the database on Machine-1 (if you have access to the historical RMAN backups of course) and you can also selectively duplicate certain tablespaces from Machine-1 by skipping those you want to retain on Machine-2.

In this case, your scenarios 1 & 3 will be OK but 2 may not be. As HJR mentioned, try it yourself and let us all know how you get on :-)

RMAN duplicate is not always the best solution for a copy but if you already use RMAN for your backups it makes life a lot easier since it registers the database in the Catalog (if you are using one) and gives the new Duplicated instance an unique DBID, which the old 'CREATE CONTROLFILE' method did not.

Take a look at the 'Duplicating a Database with Recovery Manager' chapter of the RMAN users guide, its one of Oracle's better manuals!

You might also want to consider a standby database which you keep in sync with a master database as that may be more appropriate, depending on what the instance on Machine-2 is being used for.

Regards,

Paul S. Received on Tue Sep 14 2004 - 15:14:52 CDT