USB thumb drive write speeds too fast

xaos5 · 01-19-2007, 02:56 AM

Just recently bought a USB2.0 gfm 2.0GB flash drive and wanted to test out the read/write speeds. Hdparm detects read speeds around 10.7MB/sec so that isn't an issue. My issue is with writing using dd (and cp):

Code:

~$ time dd bs=1M count=100 if=/dev/zero of=/media/disk/hugefile
100+0 records in
100+0 records out
104857600 bytes (105 MB) copied, 0.973686 seconds, 108 MB/s

real 0m0.979s
user 0m0.000s
sys  0m0.628s

I'm watching the activity LED after this command finishes and its still blinking for a couple minutes before it stops. How can I change or workaround this caching effect? (I really wish the above was true BTW

)

xaos5 · 01-19-2007, 03:04 AM

I solved my own problem by changing /dev/zero to /dev/urandom. Write speed is 2.6 MB/s (105MB in 40.7524sec)