3 Replies Latest reply on Jun 11, 2010 10:17 PM by 799875

    SCP/SFTP stalls on size limit

      I'm trying to transfer files using SCP/SFTP between Solaris 10 systems and between Solaris 10 and Red Hat Linux 5.4 systems. Between Solaris machines, there doesn't seem to be a problem. However, when trying to transfer from Solaris to/from the RHEL system, transfers always stall at approximately 22M. I've tried reducing the mtu on the RHEL system (+ifconfig eth0 mtu xxxx+) and this does increase the limit before it stalls, but still anything above 45M cannot be transferred. There are no quotas set on any system and there is plenty of disk space. Searching on the web did not yield any useful ideas.
      I can use Putty on a Windows system to act as an intermediary, getting from the Solaris system and putting to the Linux system, and transfer a 115M file okay. This is obviously a clunky work-around and doesn't allow for scripting of transferring files. This would seem to be a problem with SSH on the Linux system I'm guessing, although I haven't been able to rule out something on the Solaris system - what parameters in SSH configuration control this? Why did changing the mtu change, but not eliminate, the problem?
        • 1. Re: SCP/SFTP stalls on size limit
          Do you a firewall in between the hosts?
          This seems to be a high throughput behaviour.
          We had the same problem and took us some time to identify that the firewall is blocking the traffic after some time.

          • 2. Re: SCP/SFTP stalls on size limit
            What MTU size did you try? Is it the same on both hosts?

            • 3. Re: SCP/SFTP stalls on size limit
              Even with the RHEL firewall completely disabled, it has the same upper limit. SCP between the Solaris systems, with ipfilter running on both systems and both systems on completely different networks, is not a problem. Between Solaris and RHEL, same network but different subnet, RHEL with no firewall running (only while troubleshooting this, don't panic), still a problem. Using PuTTY SFTP from/to any of the systems is fine, even though on different networks. The mtu on the RHEL was the same as the Solaris systems (1500) - changing values on the RHEL increased the upper limit but still hit a ceiling. Only have one RHEL system so I can't see whether RHEL-RHEL transfers are affected, only those between Solaris, PuTTY on Windows, and the one RHEL system.