[geeks] Network Slowness

[Sridhar Ayengar]

Doug McLaren wrote:
> | > I work for a company that makes network backup software for virtual
> | > machines, I've done every test under the sun for checking network
> | > throughput :)  You will almost never see more than 20 MB/s on
> | > SSH/SCP/SFTP transfers, not matter how fast your media is.
> | 
> | Anyway, I'd be happy with 20MB/s.  I'm getting *5*.
> 
> Then try another protocol.  ftp, rsh/rcp, smb, etc.  The nc example
> you were given is excellent -- it even removes disk I/O as a
> bottleneck.
> 
> Don't blame the hardware or OSs until you've tried something that's
> not encrypted.  They are absolutely right -- ssh can't keep up with
> local network speeds, even on the fastest hardware.  This HPN SCP
> stuff is interesting, though it looks like a lot of their speed
> increase also comes from using the `none' encryption method (which
> should greatly reduce cpu as a bottleneck.)

But I've gotten faster speeds on (100Mbps) FDDI *with identical 
encryption turned on*.  I seriously doubt my FDDI hardware performs any 
hardware acceleration of SSH encryption.

These machines are *ridiculously* fast.  I get twice the rate with SFTP 
transfers over 100Mbps ethernet at work on machines which are an order 
of magnitude slower.

The only differences I can spot between the setup at work and the setup 
at home are that I'm using a HP Procurve gigabit switch at home, whereas 
at work I have a Cisco 2950-24, and the machines at work (correctly) 
autoconfigure themselves to 100BASE-TX instead of the 1000BASE-T I have 
at home.

Peace...  Sridhar