An Interesting thought-maybe...

dean gaudet dean-list-rdiff-backup@arctic.org
Wed, 19 Jun 2002 15:16:50 -0700 (PDT)


On Wed, 19 Jun 2002, Spicer, Kevin wrote:

> However 99% of zip files consist of the original filename with a suffix, if
> it was possible to summise which file had been zipped and how and just
> replicate this action on the remote machine this would likely be much
> quicker.

i re-read andrew tridgell's thesis regarding rsync again this weekend and
he touches on this issue.  (it's linked off of
<http://samba.anu.edu.au/~tridge/>).

> In theory a neat idea I think (even if I do say so myself).  I suspect
> actually trying to implement this would be much more difficult.  Several
> complicating factors I can think of...
> different zip formats (zip gzip bz2 etc.)
> different levels of compression (do zip files record this in their
> metadata?)

it's not even just a gzip -5 vs. gzip -9 difference... it's varying
versions of gzip (and possibly also variances due to processor
architecture?).  unless you can be 100% certain that you'll generate the
same compressed file on both sides of the link you can't use this
technique.

-dean