Re: [BackupPC-users] rsyncd full backup

On Mon, Oct 28, 2013 at 10:08 PM, Sharuzzaman Ahmat Raslan
<sharuzzaman AT gmail DOT com> wrote:
> Hi,
>
> I have implemented BackupPC for my customer.
>
> Initially, the backup transport is SMB, but recently, I noticed a lot of
> machine backup (full and incremental) is not able to complete in 8 hours,
> due to large number of file, and big file size.
>
> Last week, I installed DeltaCopy (rsycnd server for Windows) on one machine,
> and change the backup transport to rysncd. The backup runs well.
>
> But today, I noticed, when BackupPC is running a full backup on the machine
> that have rsyncd, it still takes 8 hours to do full backup.
>
> Which is I considered weird, because rsync suppose to compare that full
> backup, with the previous full backup (or previous full + incremental), so
> that only modified file is transferred.
>
> That is my expectation when I plan to use rsyncd.
>
> Any explanation why BackupPC is not running in this way? Any configuration
> that I can changed to make it work like what I expect?
>

Rsync will only transfer the changed data, but in full runs the
contents of the files are read at both ends and compared with block
checksums, so it takes some time.  Incrementals runs will quickly skip
files where the file timestamps and lengths are identical.   See the
section on 'Rsync checksum caching' in
http://backuppc.sourceforge.net/faq/BackupPC.html regarding a way to
avoid having to read/uncompress on the server side after 2 fulls have
completed, but the data is always read on the target side.

-- 
   Les Mikesell
     lesmikesell AT gmail DOT com

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