Re: Recovering database with no backup!

Hi Yanick,

Sounds like you had a bit of fun these past few days. That's the ticket ;)

At the risk of repeating myself, there are three key things (or golden rules) you require to completely recover your database:

1. A complete backup of your database that includes as a minimum your control files and all your data files. It doesn't particularly matter if this backup is hot or cold so long as the backup is on a separate device from your original files (as someone on a recent thread learnt the hard way).
2. All the redo logs generated since the oldest backed up file (and the only way to guarantee this is to have your database running in archivelog mode)
3. A DBA who knows what they are doing ;)

With respect to rule 1, if you don't backup your database, then recovery becomes a tad difficult. The only exception to the backup rule is if you have created a tablespace (or added a new datafile to an existing tablespace) between your regular backups. So long as you have all the redo logs that have been generated since the new datafile was created (which rule 2 suggests you should have), then complete recovery is still possible. Instead of restoring the corrupt datafile you can simply recreate the file with the ALTER DATABASE CREATE DATAFILE command and complete recovery as normal.

With respect to rule 2, the redo logs are possibly more important than the backup files themselves (as suggested above). If you don't ensure a complete set of redo logs between backups, then you are suggesting a complete restore from a previous backup is an acceptable recovery strategy (and the subsequent loss of changes). If it is great, if it isn't then protect these little mammas.

With respect to rule 3, you are on your way to meeting this criteria. It only comes with adequate training and experience. Proactive testing of both your backup strategies and of your personal skills will help to ensure you know what to do when you really need to.

If you remember the three golden rules then you're going to be OK and worrying about how to recover a database with no backup becomes an irrelevant issue.

Cheers

Richard

"Yanick Hudon" <yannik_at_sympatico.ca> wrote in message news:E15a9.108$z21.45462_at_news20.bellglobal.com...
> Hi all,
>
> Sorry if the post is a little bit long, but i think it worth to tell
if
> ever someone else has the same problem.
>
> After 3 hard days working on a recovery and some reading with any
> advices from you, i succeeded
> to recover my production database but i want more explanation and wich
> way i can do a backup right
> away.
>
> Here's the steps i've made:
>
> 1. Reformat the hard disk;
> 2. Reinstall Oracle;
> 3. Recreate database (for havin the control files and all data files);
> 4. Copy all the datafiles and control files i had on CD to the
location
> wich Oracle put them;
> 5. After the message: ORA-00600: ORACLE initialization in progress or
> shutdown when i tried to connect:
> a) I started RMAN and issued the following command: RECOVER
> DATABASE;
> and RESTORE DATABASE;
> b) I still got errors on those command, i started Oracle
Entreprise
> Manager to see the database status;
> c) It gives me Status Mounted, so i tried to open the database and
> on each time it gave me the missing
> files;
> d) I copied the files requested to the locations that Oracle
> Enterprise Manager was telling me;
> 6. When the database got the status open, i succeed to start SQL on
the
> database and all the datas were there.
>
> BTW: If ever you're using tablespace, be sure to have a copy of them
> when doing this procedure, otherwise
> i think taht you won't be able to recover.
>
> Now the lessons i've got from this crash:
>
> 1) Be sure to always have a backup of the database (even if i still
> don't know how);
> 2) If #1 is not available, at least get a copy of all the control
files,
> data files, tablespace you're using;
> 3) If you don't have #1 or #2, you're in real trouble.
>
> Last thing: When you're doing this procedure, ensure that you'll be
able
> to recreate all the disk partitions
> like they were before (logical, extended, and
physical
> partitions).
>
> Thanks to all who helped me in this wonderful adventure.
>
>
Received on Sun Aug 25 2002 - 22:58:19 CDT