Les Mikesell wrote at about 14:26:47 -0500 on Friday, August 28, 2009:
 > Jim Wilcoxson wrote:
 > > Michael - I have a new LInux/FreeBSD backup program, HashBackup, in
 > > beta that I believe will handle a large backuppc server.  In tests, it
 > > will backup a single directory with 15M (empty) files/hardlinks, with
 > > 32000 hard links to each file, and can do the initial and  incremental
 > > backups on this directory in about 45 minutes on a 2005 AMD box with
 > > 1GB of memory.
 > > 
 > > HashBackup can also send backups offsite via FTP, ssh accounts, or to
 > > Amazon S3.  I'd be very interested in feedback if anyone would like to
 > > try it on their BackupPC server.
 > > 
 > > The beta site is:
 > > 
 > > http://sites.google.com/site/hashbackup
 > > 
 > > Of course, you're welcome to contact me via email with questions.
 > 
 > What kind of speed would you expect from this on real files?  I let it 
 > run about 20 hours and it had only made it halfway through a pool of 
 > around 600 gigs (where an image copy of the partition takes a bit over 2 
 > hours).   Should incrementals be faster if it ever makes it though the 
 > first run?
 > 

I would be interested in knowing more about how hashbackup works.

Earlier Holger and I (and perhaps others) had a thread about how to
use the special structure of the Backuppc pool and pc directories to
speed backups. In particular we know that all the relevant inodes
(other than zero length files and directory entries) occur exactly
once in the pool tree. Similarly, every non-zero length file in the pc
directory (other than the log files and info files at the top level)
corresponds to exactly one entry in the pool directory. Also, for
incrementals, we know that inodes in general don't change except for
the limited case of chain renumbering which itself could be
potentially tracked.

If hashbackup doesn't use this special structure to its advantage then
I would indeed expect it to be substantially slower than a simple
low-level filesystem copy. On the other hand, if the structure is used
to advantage then a copy could conceivably be done with limited
overhead and roughly speaking with O(n) or at most O(n log n) scaling.


------------------------------------------------------------------------------
Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day 
trial. Simplify your report design, integration and deployment - and focus on 
what you do best, core application coding. Discover what's new with 
Crystal Reports now.  http://p.sf.net/sfu/bobj-july
_______________________________________________
BackupPC-users mailing list
BackupPC-users AT lists.sourceforge DOT net
List:    https://lists.sourceforge.net/lists/listinfo/backuppc-users
Wiki:    http://backuppc.wiki.sourceforge.net
Project: http://backuppc.sourceforge.net/