[CentOS] SFTP - stalled - on large files

On 12/21/09, Sean Carolan wrote:
I have an SSH server that was set up for a client, and every time we
try to upload large files via SFTP or scp, the transfers speed quickly
slows to zero and gives a - stalled - status message, then
disconnects. Here is an example:

ftp> put iTunesSetup.exe iTunesSetup.exe
Uploading iTunesSetup.exe to /home/scarolan/iTunesSetup.exe
iTunesSetup.exe 0% 704KB 0.0KB/s -
stalled -debug1: channel 0: free: client-session, nchannels 1
Read from remote host ftp.authoria.net: Connection reset by peer
debug1: Transferred: stdin 0, stdout 0, stderr 66 bytes in 203.9 seconds
debug1: Bytes per second: stdin 0.0, stdout 0.0, stderr 0.3
debug1: Exit status -1
Connection closed

I have no idea why this is happening. Can anyone point me in the
right direction?
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On Mon, Dec 21, 2009 at 7:06 PM, ??? wrote:

I met the same as you, but always due to the bad network connection.

Sean Carolan wrote:
On Mon, Dec 21, 2009 at 7:06 PM, ??? <myhnet at gmail.com
wrote:

I met the same as you, but always due to the bad network connection.


I should probably provide some more information, the server is a VMware
guest running CentOS 5.3. It's using the vmxnet driver for the eth0
connection. IPv6 is disabled.

I'm not sure what would cause that, but I'd use rsync over ssh instead of sftp
anyway - and use the -P option to permit restarting.

Sean Carolan wrote on Tue, 22 Dec 2009 03:08:53 -0600:

The software the client is
using is WinSCP which does have a restart feature, however it's not
working for us.

Tell him to switch WinSCP to SCP mode.

Kai

-----Original Message-----
From: centos-bounces at centos.org [mailto:centos-bounces at centos.org] On
Behalf Of Sean Carolan
Sent: Tuesday, December 22, 2009 6:13 AM
To: CentOS mailing list
Subject: Re: [CentOS] SFTP - stalled - on large files
Tried that, it still fails the same way. Here's the short list of
what I've tried to troubleshoot this:

Used SCP via the gui and command line
Used SFTP via the gui and command line
Ran yum update to bring all packages up to date
Tried stock CentOS sshd daemon (version 4.3), as well as sshd built
from source (version 5.3)
Adjusted MTU settings
Reinstalled virtual network card
Updated vmware tools and network card driver
Tried vmxnet as well as e1000 drivers

At this point I don't know what else to try. I'm thinking that it's
either a problem with VMWare, or perhaps our load balancer that is
routing the packets back and forth. Hopefully one of the vendors will
be able to help solve the problem. In the meantime we are building
out a physical server to test whether vmware is the issue or not.

If anyone else has seen this problem before or has suggestions please
post them here. Thanks.

Just an idea or thought on it. ?You never said what the file size was or did
you? ?My idea is that is, there not a file size limitation on transfer to
and from the server? ?I thought there was? ?Check you vsftpd.conf out or
what ever ftp server your running for the size limitation. ?Maybe some help
or maybe not?

Sean Carolan wrote on Tue, 22 Dec 2009 05:12:52 -0600:

Here's the short list of
what I've tried to troubleshoot this:

Load balancer... is that set up to maintain connections, or will it, like IBM's
WebSeal, go to whichever server is next/least used in the middle of a connection?

and execute "sysctl -p" to apply it. ?You can also use "sysctl -w
net.ipv4.tcp_sack=0" to turn it off temporarily. ?Our file transfers worked
just fine after the change.

I realize there are differences our situation and yours and this might not
work in your case. ?Given the length of this thread, though, it might be
worth a try!