(wrong string) €“ why restore needs older backups?

From: John Hurley <johnbhurley_at_sbcglobal.net>
Date: Sun, 26 Jul 2009 06:06:34 -0700 (PDT)
Message-ID: <e7191700-93f9-49b1-8c20-f6753856ee2c_at_k1g2000yqf.googlegroups.com>

On Jul 26, 4:26am, zigzagdna <zigzag..._at_yahoo.com> wrote:
> I am on Oracle on HP UNIX 11.2
> I have always been doing rman level 0 backup using commands like:
> backup as compressed backupset
> level 0 incremental
> Format 'dbfile_%U%_%t'
> database;
> I thought level 0 incremental is full backup, i.e., does backup of
> every block in the file.
> My backup was done on July 20,2009 6:00PM and ended on 6:30PM.
> Now I am doing point in time recovery to restore database until July
> 20, 6:31PM.
> Restore should only need backup files from July 20, 2009 6:00PM
> onwards, But for some reason
> restore requires backup files as old as from July 10, 2009.
> I thought level 0 incremental does full backup, i.e, it does not need
> older backups.
> Can any one explain why? Does it have to do with use of compressed?
> I will think in I just did level 0 (without incremental), then for
> sure I will not need older backups. Using level 0 compressed will do
> the same, i.e., full backup without requiring older backups.

Well the simple answer is that you are thinking incorrectly.


When rman starts a level 0 incremental it checks to see when the last level 0 was taken and gets blocks changed since that level 0.

If it cannot see/find a previous level 0 incremental backup then it gets a full backup.

One strategy is to move older backups off to tape ( sometimes without even using rman or telling rman about that ) ... deleting the old backup ... doing a cross check ... then doing a level 0 incremental.

Bottom line you need to both understand what you are doing and test your backup strategy so you don't surprise yourself when you actually have an important recovery operation needed to perform. Received on Sun Jul 26 2009 - 08:06:34 CDT

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