Tyler MacDonald <[EMAIL PROTECTED]> writes:
> Brian Eaton <[EMAIL PROTECTED]> wrote:
>> http://rsync.samba.org/rsync-and-debian/rsync-and-debian.html
>>
>> Has anyone ever done some log file analysis to figure out how much
>> bandwidth would be saved by transferring package deltas instead of
>> entire new packages?
Look at zsync and help develope it far enough so it can look into
debs. Without that the gain is practicaly 0 or less.
> Slightly off-topic, but I never realised until I read that article,
> how similar rsync and bittorrent are! The whole "storing checksum files on
> an HTTP server" sounds exactly like what BitTorrent is already doing. :-)
>
> Cheers,
> Tyler
Not very similar.
Bittorrent has a per chunk hash so it can validate each chunk when it
recieves it instead of waiting for the full file. It won't see if a
chunk is present at some other position in the file, not even if that
position is also on chunk boundaries.
Rsync has a per chunk Alder-32 and md4 checksum. Those chunk checksums
are compared to a chunk at every byte position in the file. The
Adler-32 checksum is fairly weak but it can be updated from one
position to the next with minimal work. Only when it matches does
rsync compute the expensive md4 checksum for the block.
The only thing that is simmilar is the "per block" when generating the
checksum, which is basicaly nothing.
MfG
Goswin
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