Re: Backups using storage system mirroring/splitting

In article <40181b3d$0$4256$afc38c87_at_news.optusnet.com.au>, Howard J. Rogers wrote:

>>

It doesn't, that's true. But it doesn't know about sequence #5005 and #5006 *at all*. At the time of the "alter database backup controlfile", sequence #5005 and #5006 were not even generated yet. Those sequences were generated in the time between the creation of the copy of the controlfile, and the split-off of the database. This means that the controlfile-copy (which is copied to system B to start the database) doesn't know about sequence #5005 and #5006, but those sequences are in the redolog files. Applying them from the redolog file works, but applying them from the generated archived logs doesn't work.

> I have to say as well that you are dicing with death by splitting mirrors

        [...]
> the rest of that block. That's a fractured block, and can't be recovered.

I'm aware of this. This is still only a testing environment, so any problems now aren't fatal, however, I'll add 'begin backup' / 'end backup' to the procedure. It'll only be in backup mode for half a second.

> A being applied to B] cannot happen. And secondly, I hope this isn't a
> production system because this is not a valid hot backup method.

It's not. Production backups are still made by consistenly shutting down the database and backing up the datafiles. Much simpler. :-)

Thanks for your reply,

-- 
Jurjen Oskam

PGP Key available at http://www.stupendous.org/