sudo hdparm -tT /dev/sda

 /dev/sda:
 Timing cached reads:   23330 MB in  2.00 seconds = 11679.09 MB/sec
 Timing buffered disk reads: 420 MB in  3.01 seconds = 139.49 MB/sec

sudo dd if=/dev/zero of=output bs=8k count=128k; sudo rm -f output
 131072+0 records in
 131072+0 records out
 1073741824 bytes (1.1 GB) copied, 4.91353 s, 219 MB/s