Thomas Birnthaler wrote at about 00:00:53 +0100 on Friday, January 9, 2009:
 > Hello,
 > 
 > 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 

Someone has written a bash routine called I think
BackupPC_deleteBackup (see:
http://backuppc.wiki.sourceforge.net/How+to+delete+backups) that
allows you to delete individual backups -- either full or incremental
-- along with any dependent higher level incremental backups. It is
necessary to also delete the dependent backups or else they are no
longer accurate as-is (note the program I wrote BackupPC_deleteFiles
goes through a *lot* of painful chains and cases to allow you to
delete individual files from individual backups but it would be very
slow to extend this to an entire backup).

 > 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.
 > 
You need to also delete the higher level incremental backups or they
will be wrong/meaningless. Also you probably want to adjust the backup
info file -- this is done correctly by the program I reference above.

 > 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?
NOPE - incremental backups by definition are meaningless/invalid if
you delete lower level full or incremental backups on which they depend.
 > 
 > 2. What is real benefit of incremental backups compared to full backups?
Speed of backup.
 > 
 > In both cases only changed/new files use disk space according to the 
 > hardlink 
 > concept of BackupPC.
 > 
 > 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.
Seems odd...
 > 
 > Thanx
 > Thomas Birnthaler
 > -- 
 > OSTC Open Source Training and Consulting GmbH / HRB Nuernberg 20032
 > tel +49 911-3474544 / fax +49 911-1806277 / http://www.ostc.de
 > Delsenbachweg 32 / D-90425 Nuernberg / Geschaeftsfuehrung:
 > Thomas Birnthaler / +49 171-3047465 / tb AT ostc DOT de / pgp 0xFEE7EB4C
 > Hermann Gottschalk / +49 173-3600680 / hg AT ostc DOT de / pgp 0x0B2D8EEA
 > 
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