On Sat, 20 Nov 2010 18:17:23 -0600, Jay Leafey wrote: > Les Mikesell wrote: [...] > This does ring a bell, but the circumstances were a bit different. In > our case we were transferring large files between "home" and a remote > site. SFTP/SCP transfers were stalling part-way through in an > unpredictable manner. It turned out to be a bug in the selective > acknowledgment functionality in the TCP stack. Short story, adding the > following line to /etc/sysctl.conf fixed the issue: > >> net.ipv4.tcp_sack = 0 > > Of course, you can set it on-the-fly using the sysctl command: > >> sysctl -w net.ipv4.tcp_sack=0 > > It helped in our case, no way of telling if it will help you. As usual, > your mileage may vary. Googing around, I get the impression that disabling SACK might lead to other problems. Any thoughts on this? Thanks, Mike.