Using zsync for .deb downloads: initial benchmark results

[Matt Zimmerman]

On Tue, Jul 14, 2009 at 07:19:31PM +0300, Lars Wirzenius wrote:
> * rsyncable: This makes it easier for zsync to do magic things with gzip,
>   by recompressing the gzipped tarballs within the .deb files with gzip
>   --rsyncable. This provies a lot of improvement. Saving a quarter of
>   the bandwidth is already fairly significant, especially since the
>   size impact on the .debs is less than 1%.
> 
> * rsyncable2: This tests whether zsync's gzip magic works better if the
>   gzip compression is the outermost layer. This is not a realistic option
>   for the archive, but provides a data point for comparisons. Turns out,
>   the differences are insignificant.
>   
> * rsyncable3: Some packages use lzma or bzip2 compression of the
>   tarballs within the .deb. This benchmark converts those to be
>   compressed with gzip --rsyncable. This improves things a bit compared
>   to just rsyncable, at a 17% increase in size compared to rsyncable.
>   Because most of the packages using lzma are OpenOffice.org related,
>   it is probably not realistic to make them use gzip --rsyncable due
>   to CD size limits, but it might be possible to use them for updates
>   that don't get put into CDs.

Do you have figures for how much the size of the .debs increased in each of
these scenarios?  We obviously need to take this into account as a cost of
the change, particularly considering the limitations on the size of the
ISOs.

-- 
 - mdz