File Offsets for SCP (patch)

[rapier]

It's really a user interface issue. We're trying to minimize the 
complexity so we don't have to keep explaining to our users how to do 
things. While we have some really smart users they're more familiar with 
climate modeling than dd. Eventually we hope to use this with a manager 
application to chunk TB+ size files so we can more them in parallel 
(possibly dmover). We we have get close to 1Gb speeds transcontinental 
now with SSH we run into the slow start issue. By parallelizing the 
transfer even if we hit congestion we don't spend as much time in slow 
start in aggregate. In that case using dd may make more sense over all.

However, for right now if we have a user that drops the connection 90% 
of the way through a 2 day file transfer this ends up being a useful 
tool for them (which what happened last last week).

Really, though it's just something we found useful which I thought to share.

Alex Bligh wrote:
> 
> 
> --On 19 November 2010 15:27:34 -0500 rapier <rapier at psc.edu> wrote:
> 
>> I don't know if anyone would be interested in this but I'm including a
>> patch to allow for offsets when transferring files with SCP.
> 
> Out of interest, why was something like
>  ssh foo.example.com dd [dd options] file -  | dd [dd options] - file
> 
> not sufficient?
>