always copy the whole file?

[bob parker]

On Mon, 4 Aug 2003 12:55, AndyWu wrote:
> Here's how it works in my 2 computers.
>
> First, on auk2
> # rsync -a auk1::pub/linux.iso .
> It takes about 4 minutes. Everything is fine.
>
> However, after doing this on auk1,
> # echo "hello" >> /pub/linux.iso
>
> Then, on auk2
> # rsync -a auk1::pub/linux.iso .
>
> The execution time of the first command is still 4 minutes.
> I think it's supposed to be much shorter than the first case?
> The same results appear in local rsync, too.
> Is there anything wrong with my commands?
>
Andy,

I'm no expert on the use of this excellent program, but there is some 
overhead incurred when the client initiates a transfer. Checksums have to be 
calculated and sent to the server before any transfer starts. FWIW I 
corrected a ~700meg iso in Australia from a server in Germany in about 6 
minutes. The iso had been created by ftp download using inumerable resumes on 
a dialup link. Fairly obviously there was not a lot wrong with this iso, 
which is what would be expected.

This link explains the checksum procedure in depth:
	http://rsync.samba.org/tech_report/

HTH
Bob Parker