Re: ftp mirrors

[Jason Molenda <jason-swarelist@molenda.com>]

On Sun, Jun 11, 2000 at 11:24:09AM -0400, Jim Kingdon wrote:

> > You're suggesting that rsync is clever enough to see two files on
> > the server, foo-2000-06-09 and foo-2000-06-10, see that the client
> > already has foo-2000-06-09, and make the leap that the -09 and -10
> > files are probably pretty close to each other, so do a diff between
> > the server's -09 and -10 and send that diff?
> 
> If rsync just concatenates the files or something equivalent it should
> be able to get this result without a special case (at least some of
> the time).  See
> 
> http://rsync.samba.org/rsync/tech_report/
> 
> especially the section on "checksum searching".  Of course it would be
> good if someone would actually test it to verify this happens in real
> world cases like snapshots.

rsync doesn't concatenate files like that AFAIK - the whole discussion
about checksum search is only relevant to when a file that exists
on both the server and the client has changed and rsync wants to
find the block that change.

Most importantly, all of this is irrelevant to Andrew's reported
problem.  Andrew says that a developer complained that they had to
download full tarballs every day while following a release process.

I am at a loss to guess why Andrew made a leap from that problem
to the solution of having a copy of the ftp dir with uncompressed
versions of the tarballs, and offering rsync access to that.  I'm
unable to understand what (a) this has to do with the problem Andrew
described (was the developer actually rsync'ing the gdb ftp dir?
I don't think I've ever seen anyone download snapshots via rsync)
(b) why the developer shouldn't just download diffs, and finally,
(c) what benefit, exactly, is gained by having uncompressed tarballs
with rsync.

Maybe Andrew is just throwing out non-sequitors to frustrate me or
yank on my chain - I'm at a loss of what the point of this discussion
is.  God forbid an ftp mirror site mirrored the uncompressed versions
of the ftp directory; the communication between the mirror site
and sourceware would be compressed, but all of the files in the
mirror site's ftp dir would be uncompressed, just like the uncompressed
dir on sourceware.  It'd be a huge disaster.

Jason