Rsync-ing a data stream (named pipe?)

[Ian Harris]

Hi,

I'm currently doing a remote backup of a MySQL database by using 
mysqldump to create a file, then using rsync to transfer this file to a 
backup server.  It works OK, except that the file is rather large and 
the backup (and everything else!) fails when I exceed my diskspace 
quota.  I'm also running fairly close to my bandwidth quota, so simply 
mysqldump-ing everything over the network isn't an option either.

I was wondering whether rsync can be persuaded to sync the "contents" of 
a local named pipe with the contents of a remote file.  That way I could 
drop the mysqldump data into the named pipe and it would efficiently 
update the backup file on the remote server.

I'm guessing that this is probably impossible, because rsync needs to be 
able to seek around within the local file, which won't be possible with 
a fifo.  But if anyone has any ideas on how to transfer a data stream 
from one machine to another, using minimum bandwidth and without the 
data hitting the filesystem on the source machine, I'd be interested to 
hear your suggestions!

Cheers,
Ian