Re: RMAN Backups/Recoveries

"Ofer Razon" <orazon_at_012.net.il> wrote in message news:bro2if$aer$1_at_news2.netvision.net.il...
> Hi.
>
> Let`s leave for the moment the issue of the PIT and the views.
> These features are given by the Storage solution I use (SVM of StoreAge).
>
> What I must understand is wheather the idea of taking incr. backups every
> day from my source DB and then make an incr. recovery to the target DB
will
> work.
> I didn`t understand yet wheather it will work or not.

I don't understand what's so difficult to understand about the word 'No', which I've used in my replies twice already.

It won't work, because there is no such thing as an incremental recovery. Recovery is a one-off process, and can't be repeated or added to without blowing away the entire database and starting from scratch each time.

Would scenarios help? Suppose you want to see a table as it was at 5.00pm on Wednesday. It would be possible to restore Monday's full backup, apply Tuesday's incremental backup, and then perform incomplete recovery, applying some of the redo generated throughout Wednesday, and thus open the database as it was at 5.00pm on Wednesday. With the database open, you could extract data as it was on Wednesday at 5.00pm.

But you then want to see the data as it was at 10.00am on Thursday? Not a chance. You would have to destroy the Wednesday-at-5 database, re-restore Monday's full backup, re-restore Tuesday's and Wednesday's incremental backups, and then recover the database to the way it was at 10.00am on Thursday. You could then open the database and see the data as it was at that time.

But then you want to see the data as it was at 1.00pm on Friday. Again: destroy the Thursday-at-10 database, re-restore the Monday full backup, re-restore the Tuesday, Wednesday and Thursday incremental backups, and then perform a recovery until 1.00pm on Friday. The database could then be opened and see the data as it was at 1.00pm on Friday.

Each time you want a new time to open the "viewing" database, you have to destroy its prior version, and re-create it from scratch using the backups of, and redo logs generated by, the "production" database.

I can't put it any plainer than that. Once a database has been recovered, that's it. If you want to recover it to a different time, you have to blow it away, and start from scratch. You can't apply further redo (ie, perform further recovery) to a database that has already been recovered and opened with a resetlogs.

> I mean that on my target DB I`ll recover once a full recovery, and
> afterwards I`ll run an incr. recovery everyday so when I`ll want to open
the
> DB it`ll contain the most lately version and data of my source DB.

Again, there is no such thing as an incremental recovery. So, to put it plainly: "No this won't work".

HJR Received on Tue Dec 16 2003 - 18:47:03 CST