Re: Rman level 0 incremental backup – why restore needs older backups?
From: zigzagdna <zigzagdna_at_yahoo.com>
Date: Sun, 26 Jul 2009 07:37:41 -0700 (PDT)
Message-ID: <b94eabd3-f498-439d-bc21-7b99c852e5c4_at_v20g2000yqm.googlegroups.com>
On Jul 26, 9:06 am, John Hurley <johnbhur..._at_sbcglobal.net> wrote:
> On Jul 26, 4:26 am, zigzagdna <zigzag..._at_yahoo.com> wrote:
>
>
>
>
>
> > I am on Oracle 10.2.0.3 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.
>
> http://download.oracle.com/docs/cd/B19306_01/backup.102/b14192/bkup00...
>
> 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.- Hide quoted text -
>
> - Show quoted text -
Date: Sun, 26 Jul 2009 07:37:41 -0700 (PDT)
Message-ID: <b94eabd3-f498-439d-bc21-7b99c852e5c4_at_v20g2000yqm.googlegroups.com>
On Jul 26, 9:06 am, John Hurley <johnbhur..._at_sbcglobal.net> wrote:
> On Jul 26, 4:26 am, zigzagdna <zigzag..._at_yahoo.com> wrote:
>
>
>
>
>
> > I am on Oracle 10.2.0.3 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.
>
> http://download.oracle.com/docs/cd/B19306_01/backup.102/b14192/bkup00...
>
> 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.- Hide quoted text -
>
> - Show quoted text -
All the documenation I have read is:
A level 0 incremental backup is the base backup for subsequent incremental backups.
It copies all blocks containing data, backing the datafile up into a backup set just as a full backup would. The only difference between a level 0 incremental backup and a full backup is that a full backup is not included in an incremental strategy. That is after taking full backup , you can’t perform incremental backup over.
If incremenatl level 0 did incremenatl since last level 0, one will need lots of older backups which makes no sense. Somehow, I cannot read the URL in your response. Received on Sun Jul 26 2009 - 09:37:41 CDT