Rsync stops responding via SSH

[Larry Hall (Cygwin)]

Roald Hendriks wrote:
> Dear reader(s),
> 
> First, I'll state the goal: Synchronizing data using rsync on CygWin
> (win2k3 servers) via a data 'pull' and ssh
> 
> On a remote system, data is exported to files, and rsync is used to
> synchronize the data from a remote server to our local server (so a
> data 'pull').
> 
> When synchronizing the data (rsync -e "ssh -p 1500" --progress -v
> --timeout=600 --compress --times user@localserver:/folder/*.*
> /localfolder/.), after some files being updated, rsync stops
> responding and a timeout occurs. On the remote server, rsync remains
> running as a process as if it 'hangs'.
> 
> Note that the connection via port 1500 works fine, directory contents
> can be retrieved via rsync without problems.
> 
> When using the '--whole-file' option, no problems occur, data is
> transfered perfectly, however, this is ignoring one of the key
> features of rsync.
> 
> I've noticed some mails with regard to this issue in this mailing list
> on August 14th 2006 (
> http://cygwin.com/ml/cygwin/2006-08/msg00487.html ). A follow-up,
> mentions the following:
> 
> --- begin of copy from follow up message ---
> 
> Yes its a known issue for the exact situation you explain. Pulling
> files from a hosting using ssh+rsync under CYGWIN.
> 
> My current understanding of the situation is with the non-blocking
> implementation of pipes under CYGWIN does not return EAGAIN even the
> pipe buffer is full and starts to block.
> 
> This causes rsync to become blocked on a write call to send data to
> ssh, and ssh becomes blocked also on a write call sending data to
> rsync. This causes a deadlock.
> 
> Since rsync can work in blocking and non-blocking mode its really SSH
> that end that has the problem.
> --- end of copy from follow up message ---
> 
> Is it possible that I'm suffering from this known issue?
> 
> Is there a patch available?
> 
> I'm using OpenSSH 4.5p1-1 and rsync 2.6.6. I have even compiled rsync
> 2.6.9, but this has not resolved the issue.
> 
> In order to rule out a server issue, I was able to reproduce the
> problem on another server as well (using a fresh install of CygWin).

Yes, this is a known and long-standing issue with rsync on Cygwin.  There
has been much talk about it and some attempts to fix it but, to my
knowledge, no one is currently working on it.  So, for now, it is a
limitation of rsync on Cygwin.

-- 
Larry Hall                              http://www.rfk.com
RFK Partners, Inc.                      (508) 893-9779 - RFK Office
216 Dalton Rd.                          (508) 893-9889 - FAX
Holliston, MA 01746

_____________________________________________________________________

A: Yes.
 > Q: Are you sure?
 >> A: Because it reverses the logical flow of conversation.
 >>> Q: Why is top posting annoying in email?

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