Re: rman incremental merge
- From: "Don Seiler" <don@xxxxxxxxx>
- To: "Jared Still" <jkstill@xxxxxxxxx>
- Date: Tue, 5 Dec 2006 13:23:21 -0600
http://download-east.oracle.com/docs/cd/B19306_01/backup.102/b14192/bkup004.htm#BRBSC186
The text of which follows. The term "image copy" echoes throughout:
Oracle's Incrementally Updated Backups feature lets you avoid the
overhead of taking full image copy backups of datafiles, while
providing the same recovery advantages as image copy backups.
At the beginning of a backup strategy, RMAN creates an image copy
backup of the datafile. Then, at regular intervals, such as daily,
level 1 incremental backups are taken, and applied to the image copy
backup, rolling it forward to the point in time when the level 1
incremental was created.
During restore and recovery of the database, RMAN can restore from
this incrementally updated copy and then apply changes from the redo
log, with the same results as restoring the database from a full
backup taken at the SCN of the most recently applied incremental level
1 backup.
A backup strategy based on incrementally updated backups can help
minimize time required for media recovery of your database. For
example, if you run scripts to implement this strategy daily, then at
recovery time, you never have more than one day of redo to apply.
On 12/5/06, Jared Still <jkstill@xxxxxxxxx> wrote:
On 12/4/06, Don Seiler <don@xxxxxxxxx> wrote:
> The usage that I've seen and used is to start with a level 0, and from
> there on out you'd only take level 1 incrementals. Then, based on
> your recovery window, you could roll your base backup image forward,
> for example to 7 days ago, if that is your window. It saves you the
> time of not having to do another level 0, but having a recent level 0
> image to start with for recovery.
The recovery of course depends on whether the incremental was a
differential or cumalitive incremental. Cumalitives give faster backup
performance than differentials, but cause longer restoration times. This
is assuming that there is > 1 incremental level 1+ between level 0.
> The reason I stopped using it is that you HAVE to do a backup COPY. I
> didn't have the disk to hold an actual copy, and needed to have
> compression.
>
>
Somehow I have missed that part. I have backed up and restored
databases from incremental 0 and 1, but have not had to do any
backup COPY.
Can you point to a relevant doc?
--
Jared Still
Certifiable Oracle DBA and Part Time Perl Evangelist
--
//www.freelists.org/webpage/oracle-l
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