Sloooowwwww ssh/scp

Greetings all;

We're having a hard time getting data to move any faster than about 5MB/sec,
even across a 1GB link.

We're moving between fairly beefy Sun systems, with openssh compiled
by hand. SSH Version is 4.6p1 compiled against openssl 0.9.7g. (Tried
against 0.9.8e as well, with the same results. Also tried openssh4.0p1,
to no avail.)

Network cards are 1GB, full duplex. Yes, it really _is_ full duplex, with
no mismatches at the switch. Network testing has shown no issues in either
hardware or packet errors, and FTP will happily give us 35-45MB/sec over
the same link.

We've looked into HPN-SSH (High Performance patches for SSH), but (a) they
theoretically shouldn't help with our very low-latency connection (~0.40ms
loop times), and (b) they don't.

We can get 10MB/sec running over 100baseT lines via FTP, and as I said
above, >35MB/sec over gigabit. scp just plods along at 5MB/sec on a good
day, making file transfer utterly painful, not to mention tunnelling X11
over ssh.

Any ideas? We're seeing this between any of our machines most of which are
large and fast--either AMD or Sparc processors.

Oh yeah, and before I forget--we get identically bad performance with
the built-in Sun sshd and ssh/scp clients.

Thanks,
Colin

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Relevant Pages

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    ... We're having a hard time getting data to move any faster than about 5MB/sec, ... We're moving between fairly beefy Sun systems, ... SSH Version is 4.6p1 compiled against openssl 0.9.7g. ... Network cards are 1GB, full duplex. ...
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