Find the bottleneck: disk I/O on Windows XP

PAL cuts through a lot of the amiguities and does a nice job of showing troublespots.

your problem is that you are testing too many things at once:

• disk read speed
• SSH encryption
• wireless
• SSH decryption
• disk write speed

Since you mentioned SSH I am going to assume this is a unix system...

You can rule out any problems with disk read speed with a simple

dd if=yourfile of=/dev/null #or
pv yourfile > /dev/null

on the receiving end you can do a simple disk write test

dd if=/dev/zero of=testfile bs=1M count=2000 # or
dd if=/dev/zero bs=1M count=2000 | pv > testfile

dd is not really a "benchmark" but since scp uses sequential IO, it is close enough

you can also test SSH by doing something like

dd if=/dev/zero bs=1M count=100 | ssh server dd of=/dev/null # or
dd if=/dev/zero bs=1M count=100 | pv | ssh server dd of=/dev/null

finally, to rule out SSH being the bottleneck, you can use nc to test the network performance

server$ nc -l 1234 > /dev/null
client$ dd if=/dev/zero bs=1M count=100 | pv | nc server 1234 # or
client$ dd if=/dev/zero bs=1M count=100 | nc server 1234

if you really want to properly test the network, install and use something like iperf, but nc is a good start.

I'd start with the nc test as that will rule out the most things. You should also definitely run the tests while not using wireless. 802.11n can easily max out a 100mbit port, but only if you have it properly setup.

(Ubuntu >= 12.04 defaults to netcat-openbsd. nc -l -p 1234 > /dev/null may be what you want if you're using netcat-traditional).