Re: Aspera SCP software

[Brian Long <brilong cisco com>]

On Mon, 2005-05-16 at 17:36 +0100, John Haxby wrote:
> Ed Wilts wrote:
> 
> >It does work well in practise.  The wide-area SAN people use the same
> >concept.  What appears to happen is that the transfers may go over UDP
> >instead of TCP so that you're not trying to ack every packet half-way
> >around the globe but can ack them in bunches.  The end result appears to
> >be a more consistent data flow.  
> >  
> >
> This sounds like windowing to me or am I missing something?  tcp(7) 
> talks about setting the global read and write windows to deal with high 
> bandwidth or high latency connections.   With large windows you don't 
> ack every packet, just every window'th packet don't you? (*)

In our internal transfers between two sites with ~60ms latency and
almost unlimited bandwidth (OC-12), you can only get about 1.4MB/sec on
single-threaded connections with default settings in RHEL 3.  However,
if you add a multi-threaded rsync script in front of it, you can almost
saturate the WAN.

We use mdo, a tool written internally but recently open-sourced:

https://sourceforge.net/project/showfiles.php?
group_id=34678&package_id=140141

mdo is also named mscp, mrsh, etc and it's behavior changes depending on
how you call it.  Of course, this is the opposite of what Ed wants to
do  :)

/Brian/

-- 
       Brian Long                      |         |           |
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