sync; dd if=/dev/zero of=tmp4bench bs=1M count=1024; dd if=tmp4bench of=/dev/zero bs=1M count=1024; rm -f tmp4bench ; sync
hdparm -Tt /dev/sda
sync; dd if=/dev/zero of=tmp4bench bs=1M count=1024; dd if=tmp4bench of=/dev/zero bs=1M count=1024; rm -f tmp4bench ; sync
hdparm -Tt /dev/sda