On Fri, Jan 09, 2009 at 12:00:53AM +0100, Thomas Birnthaler wrote:

> we are using BackupPC and it works perfect on different places.
> But we have 2 questions on it:
> 
> 1. We wonder why neither the GUI nor the commands offer a possibility to 
> delete backups (full and incremental). If e.g. the backup partition is filled 
> up, this would be very helpful.
> 
> As far as we understood the concept of using hardlinks and different 
> directories for each backup + a hash pool for each file it seems to be very 
> easy to delete a backup NN.
> 
> Just delete recursively the backup directory NN and the nightly run will 
> really destroy all orphaned files with a hardlink count of 1.
> 
> If a full backup is deleted that way, incremental backups depending on it 
> then 
> depend on the next earlyer full backup and work as before. Same is true for 
> incremental backups. So the GUI works as before and the creation of new 
> backups too.
> 
> Is that idea correct?

Almost. ;-) You should not delete a full backup if there are some
incrementals depending on it. Rule: Only delete a level-n incremental if
there is no level-n+1 incremental (with n=0 for fulls).

Your web view would become inconsistent (e.g. deleted files becoming
visible again).

> In both cases only changed/new files use disk space according to the hardlink 
> concept of BackupPC.
 
Yes. Fulls need some more space because they are completely filled, that
is, all directories contain hardlinks to all the files, whereas
incrementals only contain hardlinks to new and changed files -
filesystem-wise they've got holes which are filled by the CGI.

> We have also detected, that in some cases incremental backups need much more 
> time than full backups (factor 3-5) This sounds odd to us.

What transfer method are you using?

HTH,

Tino.

-- 
"What we nourish flourishes." - "Was wir nähren erblüht."

www.lichtkreis-chemnitz.de
www.craniosacralzentrum.de

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