Where is my bottleneck?

Marc Abel m-abel at columbus.rr.com
Fri Mar 12 05:48:25 GMT 2004

I did some more investigating on the ssh slowdown theory... I also found
one negative comment concerning my router (Linksys BEFSR81) which might
be throughput-related.

In a nutshell:  ssh between these two machines can run at least 43
Mbit/s.  I created a 100 Mbyte file from /dev/urandom, and ssh brought
it back (ssh majority cat delete.me >file) in under 20 seconds.  No
compression (it was reasonably random), and entirely accurate (I did
md5sums at both ends).

So I'm still seeing cat > 43 Mbit/s and rsync < 2 Mbit/s, both using
ssh.  Round trip packet time is under 0.5 ms, and I looked through a
bunch of IP tuning stuff too and my buffers and features seem fine.

I wonder what's missing here.  Even if I get this working via rsh or
direct-to-rsync-server, it's still reasonable to think it would work
with ssh.

Marc Abel
Powell, Ohio

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