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Re: [Bacula-devel] Synthetic Full backup or Consolidation
On Saturday 17 May 2008 09:43:19 Marc Schiffbauer wrote:
> * Kern Sibbald schrieb am 17.05.08 um 14:59 Uhr:
> > Item 3: Merge multiple backups (Synthetic Backup or Consolidation)
> > Origin: Marc Cousin and Eric Bollengier
> > Date: 15 November 2005
> > Status:
> > What: A merged backup is a backup made without connecting to the
> > Client. It would be a Merge of existing backups into a single backup. In
> > effect, it is like a restore but to the backup medium.
> > For instance, say that last Sunday we made a full backup. Then
> > all week long, we created incremental backups, in order to do
> > them fast. Now comes Sunday again, and we need another full.
> > The merged backup makes it possible to do instead an
> > incremental backup (during the night for instance), and then create a
> > merged backup during the day, by using the full and incrementals from the
> > week. The merged backup will be exactly like a full made Sunday night on
> > the tape, but the production interruption on the Client will be minimal,
> > as the Client will only have to send incrementals.
> > In fact, if it's done correctly, you could merge all the
> > Incrementals into single Incremental, or all the Incrementals
> > and the last Differential into a new Differential, or the Full,
> > last differential and all the Incrementals into a new Full
> > backup. And there is no need to involve the Client.
> > Why: The benefit is that :
> > - the Client just does an incremental ;
> > - the merged backup on tape is just as a single full backup,
> > and can be restored very fast.
> > This is also a way of reducing the backup data since the old
> > data can then be pruned (or not) from the catalog, possibly
> > allowing older volumes to be recycled
> This sounds like a very useful Feature.
> Would there be a way to combine this with some sort of data-deduplication?
No, we won't get data deduplication from the consolidation project.
However, deduplication at the file level (not at a block or byte level) is a
project that is in the project list. It has been on the list for a *very*
long time (since the beginning) but has always been rated very low by the
users. In the current list it is Item 7: Implement Base jobs
Now that Eric has implemented the Accurate backup project, the Base Jobs
project will be a rather easy extension of the "accurate" code. The
fundamental algorithms are very similar. I doubt that we will implement the
Base project in the next version, but it will almost certainly come in the
I had originally planned to release 3.0.0 in June or July, but will probably
push it back to September to allow a few more features to go in and to give
us sufficient time for stabilization and testing.
> Deduplication is "just" writing Metadata for a client and not
> putting the data on tape because it has already been written to tape
> by another client.
> Think of "hard-linking" Datablocks on tape.
> Further there could be an option tp specify a minimum and a maximum
> number of mediums that each data block has to be spread on.
> This would bring a real "killerfeature" useful for most users into bacula
> that is offered only by commercial enterprise backup solutions so
> far (AFAIK)
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