On Mon, Jan 12, 2009 at 12:23 PM, Graham Wooden <graham AT g-rock DOT net> 
wrote:
> Also keep in mind the TCP sliding window when going over the Internet.  You
> can have a fat pipe (on both ends), but the increased hop count and the TCP
> overhead you will only get a percentage of your pipe.  In my experiences,
> they have been about less than 1/2 of the pipe.  Unless the "backup" is
> streamed over UDP (more efficient but no error checking).

That's a good point.  The broader point, though, is that neither
Amazon nor most of the ISPs between you and Amazon are too keen to
squeeze out every last ounce of upload speed for you, so anyone
backing up more than a few gigs nightly to Amazon is going to be
unhappy - regardless of pipe size.

Note that you can use Amanda's planner to good effect, by specifying,
say, a 2G tape size, and lots of small DLEs, thereby backing up much
more than 2G of data over the course of your dumpcycle.  I use this
technique to keep my nightly backups to about 800M.

Dustin

-- 
Storage Software Engineer
http://www.zmanda.com