Re: Some Dataguard is good, lots more must be better?

On 09/20/2006 04:34:58 AM, Lawie, Duncan wrote:
>

> Say I want to push database 42 back by 2 hours 16 minutes and 42 seconds. If it is sharing a
> filesystem with a bunch of other databases which are running just fine, how do I load up the
> old files for database 42, if the snapshot is at the filesystem level? I'm reading your mail
> as saying the snapshot from time x would be a mountable filesystem? If so, do I then need to
> copy the files back to my "real" filesystem, or do I change my database control file to point
> to the new mount? The latter would appear to gradually fragment the few, large filesystem
> approach. The former doesn't seem to save me time against some other recovery mechanisms.

Duncan, Kevin is talking about NetApp which has old snapshots permanently mounted as read-only file system. Snapshots are not supported with RMAN (this may have changed since the last time I worked with that) so that, in order for the database to be recoverable from snapshots, you would need to put your database in backup mode immediately before the snapshot is taken and take it out of the backup mode after the snapshot is taken. This works pretty well. The mechanism to use for traveling back in time is, of course, database recovery. Dr. Who is still a science fiction.

-- 
Mladen Gogala
http://www.mgogala.com

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