Re: RMAN frustration

From: Hartmut Inerle <hinerle_at_aol.com>
Date: Thu, 30 Jan 2003 10:38:02 +0100
Message-ID: <3E38F27A.4030107@aol.com>

Howard J. Rogers wrote:
> "Holger Baer" <holger.baer_at_science-computing.de> wrote in message
> news:3E37FFF0.40804_at_science-computing.de...
>

>>Hartmut Inerle wrote:
>>
>>>Rogbaker wrote:
>>>
>>>
>>>>run {
>>>>allocate channel disk1 type disk format
>>>>'c:\rmanbakup\backup_012803';
>>>>backup database;
>>>>sql 'ALTER SYSTEM ARCHIVE LOG CURRENT':
>>>>}
>>>
>>>
>>>You are doing here a full backup solution. For a Point-in- time recovery
>>>is a incremental backup solution necessary.
>>>
>>>And I didn't see and archivelogs in the backup. Have a look in the
>>>documentation for the prerequesites for the point in time recovery.
>>>
>>>regards
>>>   Hartmut Inerle
>>>
>>
>>Could you please explain this a bit further? It's my understanding
>>that after a full backup I can restore to virtually any point in time
>>after the backup, since basically all I need are the rman backupset
>>and the archivelogs.

>
>
> Your understanding is correct, and incremental backups have got nothing to
> do with it. I'm not sure what point what Hartmut was making, but taking it
> at face value, he's wrong.
>
> Regards
> HJR
>
>
>

Hello,

Further explanation.

What is oracle doing during a full backup. It copies are used database blocks into a backup set. Full Backup creates something like a database snapshot. There is no information to rollback the database beyond this point in time. To reach an other point in time you need the archive log files are created after the full backup. This means you can have two ways to do a point in time recovery.

Full backup + archive log = reaching a point after the full backup.

Incremental backup + archive log = reaching a point after the initial incremental level 0 backup.

BTW: BACKUP DATABASE FULL is not equal BACKUP DATABASE INCREMENTAL LEVEL 0. The result is the same, but a incremental backup strategie can only start with a backup level 0.

regards

   Hartmut Received on Thu Jan 30 2003 - 03:38:02 CST