Re: Weird Backup, can it be done without resetlogs?

On Fri, 23 Jan 2004 20:48:48 +0100, "Francisco J. Garcia Humphries" <fjgarcia_at_e-humphries.net> wrote:

>My company is implementing a backup solution for a 2 instance (A and B) RAC
>based on the following:
>
>- At a certain time we start mirroring the database (datafiles,
>controlfiles, redologs and archives) to a disk that gets shared with server
>C.
>
>- After about two hours, when the shared disk is an exact live copy of the
>database, we issue an "alter tablespace begin backup" on the database.
>Detach the mirror disk (so it doesn't get changed any more)and the "alter
>tablespace end backup" on the production database.
>
>- At this point i would expect the database on the mirrored disk to be
>pretty similar to a database that has just crashed ¿right?.
>
>- The backup strategy is based on a new instance on server C that opens the
>database files on the mirror disk and then get's backued up by third party
>software. The problem we are encountering is that whenever we try to open
>this copy of the database with a new instance
>we need to do a RESETLOGS in order to be able to open the database. I don't
>get why i should have to open resetlogs and i need to be able to open the
>database without RESETLOGS
>
>Does anyone see a problem in the way this process copies the database? I'm
>thinking there might be a problem for Controlfiles and Logfiles. Is there
>any problem with the database being opened by a single instance when it was
>a RAC at first?
>
>Any help will be greatly appreciated.
>

Please explain why you think this process constitutes a proper backup. Please explain why you misuse mirroring in this fashion. Also please explain why you can't implement an ordinary hot backup.

--
Sybrand Bakker, Senior Oracle DBA