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Re: sshd and scp/sftp: slow throughput on windows machines

At 02:49 2006-03-18 +0100, Max Stein wrote:
>Unfortunately, the performance of the cygwin sshd server is very poor when 
>it comes to copying large files. I have made this observation on several new 
>and fast machines (3 GHz, 512 MB RAM, 100 MB/s Intel Pro network card) 
>running with Windows XP or Windows 2003 Server. The best speed achievable 
>was about 4 MB/s when copying a file from the SSH client to the SSH server; 
>when doing it the other way round, the throughput was even worse, about 2.3 
>MB/s. I tried it on three different machines running the newest version of 
>cygwin's sshd und scp/sftp. The results were approximately the same.
>Neither the client's nor the server's processor was really busy. The CPU 
>usage oscillated around 30-40%.
>Setting up the same scenario on linux yielded a completely different 
>picture. Using the Knoppix disc 4.0.2 on the client and the server machine I 
>easily achieved a throughput of 10.8 MB/ in both directions (pushing a file 
>to the server or downloading a file from it).
>What could be done to improve the performance of cygwin's SSH server? There 
>were already some older posts dealing with the same problem but nobody had 
>really a constructive idea or proposal.

1. Is it possible to increase the bandwith by having the client aggregate 
multiple sessions through a single pipe?
2. It would seem that PPTP connections can be much faster. E.g. a FreeBSD 
MPD running on a 400 Mhz Pentium II can sustain a 50 Mbit/s datastream at a
CPU usage of 25%.
W2k and XP have easy to configure PPTP clients.
(See also W2003 RAS.)


Arend-Jan Westhoff.

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