[CentOS] info about hdds in raid

Les Mikesell wrote:
> If you can see activity lights, you can 'cat /dev/sd? >/dev/null' to 
> make them busy, one at a time (where ? is a, b, c, etc).
>   

hahaha, I've done that, only my version is...

    # dd if=/dev/sdX of=/dev/null bs=512

but, same difference