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Re: [Bacula-devel] Synthetic Full backup or Consolidation

On Saturday 17 May 2008 08:52:49 Frank Sweetser wrote:
> Kern Sibbald wrote:
> > Hello,
> >
> > I am considering putting a first cut of job consolidation into the next
> > version of Bacula -- see item #3 on the y, Projects list "Merge multiple
> > backups (Synthetic Backup or Consolidation)"
> >
> > I'm considering the possibility of implementing it as a sort of
> > sub-option of Migration and Copy jobs.  The advantage is that virtually
> > all the necessary code exists, and by using Migration and Copy, the
> > Consolidate can either be a "move" or a "copy" operation.
> There may be something I'm missing, but I'm a little unclear on exactly
> what these jobs would be doing.  More specifically, would these
> consolidation operations entail duplication of volume data (ie, consolidate
> jobs X, Y and Z from volumes A, B and C into a new job Q on volume W), or
> would it just be manipulation of catalog data?

Item  3:  Merge multiple backups (Synthetic Backup or Consolidation) 
  Origin: Marc Cousin and Eric Bollengier 
  Date:   15 November 2005

  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

          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

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