You can use the following command to see the speed of a hard disk:
UBUNTU > time dd if=/dev/zero of=large_file \
> bs=4096 count=2000000
2000000+0 records in
2000000+0 records out
8192000000 bytes (8.2 GB) copied, 192.95 s, 42.5 MB/s
real 3m13.102s
user 0m6.148s
sys 1m29.718s
UBUNTU >
