Dennis Nezic
2010-03-22 17:02:47 UTC
I have run into a similar problem, although I don't get any "rcvd
adjust" debug messages -- instead my scp transfers stall -- at a pretty
predictable place too (not exactly, but to within a few megabytes). My
problem ONLY started after I upgraded my kernel (and maybe some other
things :s, from 2.6.19 to 2.6.33). My NFS transfers also started
"stalling", for many minutes (5-15min usually), although they are
retried, and eventually finish. Again, I don't think ANY of these
problems ever happened with my old kernel for a couple years.
During the stalls, netstat says the tcp connection is still
ESTABLISHED, and when I Ctrl-C the stalled scp transfer, the sshd
server logs a "Received disconnect" message. No other debug messages
are shown for me. I'll try to get a tcpdump.
adjust" debug messages -- instead my scp transfers stall -- at a pretty
predictable place too (not exactly, but to within a few megabytes). My
problem ONLY started after I upgraded my kernel (and maybe some other
things :s, from 2.6.19 to 2.6.33). My NFS transfers also started
"stalling", for many minutes (5-15min usually), although they are
retried, and eventually finish. Again, I don't think ANY of these
problems ever happened with my old kernel for a couple years.
During the stalls, netstat says the tcp connection is still
ESTABLISHED, and when I Ctrl-C the stalled scp transfer, the sshd
server logs a "Received disconnect" message. No other debug messages
are shown for me. I'll try to get a tcpdump.
First and foremost, thank you to everyone for your responses. I
checked the MTU on both sides and it's currently 1500 so I'm assuming
it's not a mismatch. My VPN is a pair of old Netscreen 5xp boxes, and
I can't find anything relating to MTU or packet size in the
configuration, but I'm still looking.
Secondly, to answer your question John, There is no persistent
connection between the servers. I could feasibly set up an NFS share
between the two but I have a sneaking suspicion that if the problem
is some sort of packet mangling by the VPN during file transfers, the
actual mechanism used to transfer the file will be irrelevant.
However, I will set this up and test it and report back my results,
most likely next Monday.
checked the MTU on both sides and it's currently 1500 so I'm assuming
it's not a mismatch. My VPN is a pair of old Netscreen 5xp boxes, and
I can't find anything relating to MTU or packet size in the
configuration, but I'm still looking.
Secondly, to answer your question John, There is no persistent
connection between the servers. I could feasibly set up an NFS share
between the two but I have a sneaking suspicion that if the problem
is some sort of packet mangling by the VPN during file transfers, the
actual mechanism used to transfer the file will be irrelevant.
However, I will set this up and test it and report back my results,
most likely next Monday.
Matt,
If you are using ssh do you need to use scp as well? Or is just
plain copy ok?
If you are using ssh do you need to use scp as well? Or is just
plain copy ok?
[...]
http://www.snailbook.com/faq/mtu-mismatch.auto.html for details.
I've looked high and low and haven't really come up with anything
definitive. Someone somewhere had mentioned fiddling with MTU
settings, but I'm not really sure what that will accomplish as I
am unfamiliar with what MTU is and does. If this question has
been answered previously, I apologize ahead of time. Thanks!
This does sound like the MTU problem to which you refer. Seedefinitive. Someone somewhere had mentioned fiddling with MTU
settings, but I'm not really sure what that will accomplish as I
am unfamiliar with what MTU is and does. If this question has
been answered previously, I apologize ahead of time. Thanks!
http://www.snailbook.com/faq/mtu-mismatch.auto.html for details.