Limitation in SCP?

Jim Kleckner
Wed Dec 15 01:00:00 GMT 2004

Corinna Vinschen wrote:

> On Dec 13 14:37, Bob Smart wrote:
>> I've discovered that in some circumstances, scp seems to get tired
>> early when transferring a largish file (around 200MB).  It copies
>> diligently for the first 20-40MB (exactly where it stops varies
>> from run to run), then CPU usage drops to zero, the file stops
>> growing on the receiving end, there's no apparent network traffic,
>> and everything just pretty much halts.  A ps shows the scp task
>> running, but not doing anything.
>> I've only seen this when copying between two W2K machines (both
>> Cygwin, both using the Cygwin SSH package, both of pretty recent
>> vintage with DLL 1.5.11).  I did my development testing between
>> Linux and NT, and I never saw this behavior in that environment.
>> It always fails with the W2K machines.
>> I also never see this happen with tar.  If I do a tar-to-tar pipe
>> via SSH, everything works even in the W2K-to-W2K environment.
>> However, I'd like to understand why I can't use scp for this.
> Hmm, that doesn't happen for me.  I tried to copy around a 200 Megs
> file between WinXP and XP<->Linux multiple times and don't see any
> hang.  Did you try with Cygwin 1.5.12, too?

Is this possibly related to the pipe hang issue that some
apps have with ssh such as mentioned here and that
Bob Byrnes is looking at?:

Bob, are you "pushing" or "pulling" the files?  It has
been noted that rsync works to push files to windows
but hangs in a similar way when pulling files from a
remote machine.  Again, it may or may not be related.


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