Batch mode creates huge diffs, bug(s)?

Matt Van Mater matt.vanmater at
Tue Mar 20 13:58:59 MDT 2012

Let me restate my last email regarding rdiff:

All of my image files are from the same Windows XP VM, created using
FOG/partimage.  Image1 is the "baseline", Image2 is Image1 + the WinSCP
binary downloaded (not even installed).

I am not imaging an Ubuntu machine.  I am using the Ubuntu machine as a
means of creating the batch file for rsync and/or rdiff.  I chose that
platform since it is a common distribution used by many and would be easy
for others to reproduce my problem.

I agree the 400 MB still looks big, but no the ONLY intentional difference
between image1 and image2 is the 2.9 MB WinSCP binary i downloaded.  My
guess is the difference is 1) due partially to the default block size rdiff
uses (512b?) AND 2) the fact that the Windows XP VM image source only had
256 MB RAM and that by default Windows XP creates a pagefile of 1.5 x RAM
size = 384 MB.  That is close enough to 400 MB for me.

I am currently running rdiff with a smaller blocksize to test #1 above,
hopefully that will force the delta to get smaller (at the expense of
longer computation time).


On Tue, Mar 20, 2012 at 3:41 PM, Joachim Otahal (privat) <Jou at>wrote:

> Matt Van Mater schrieb:
>> Alternate assessment - I ran a similar comparison against the two image
>> files using rdiff that comes with Ubuntu 10.04.4 LTS (shown up as librsync
>> 0.9.7) and have a significantly smaller delta file (closer to what i
>> expect).
> Just plain luck. If ubuntu wrote the most new files close to the last used
> blocks and only changes a few bytes (this time literally) in the middle
> then the desync happens later. The 400 MB delta still looks big, or did you
> install something big like libreoffice?
> regards,
> Joachim Otahal
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