Re: Using Debian GNU/Linux as base for commercial linux

[Philip Hands <phil@hands.com>]

> Have I missed the point of rsync?
> 
> Nearly all files I pull from the mirrors are crunched - either *deb or *z.
> Now changing even 1 byte at the beginning of a file and then recrunching
> results in a file which has nothing in common with the original crunched
> file.  At least that is my understanding and it seems to be supported by 
> the results I get in practice.  I used rsync to change linux-2.0.33 to
> 34 and it downloaded the whole 6.8 megs.
> 
> So what does rsync buy me?

If the date changes, but the file does not, rsync transfers a fraction of the 
file, mirror & fmirror transfers all of it.

rsync gets access to the real file date, so you don't get clock skew resulting 
from files being transfered between timezones.

FTP has the overhead of having to CD etc, which means that the listing of the 
archive is less efficient.

rsync writes to a temporary file, and moves it into place only at the end of
the transfer, so people are never given the opportunity to download a partial
copy of a file.

On the downside, rsyncd currently uses more memory than ftpd, because it puts 
the entire directory tree into memory at once AFAIK.

Cheers, Phil.