[CentOS] drive to standby after idle timeout?

I'd like to to put the hard drives in standby mode during periods of  
no activity. I'm just running a file server plus a couple small  
things on a Qube 3 from home, although the web stuff will increase  
it's still minimal.

On my NetBSD systems I can use atactl to do this via:

mount -u -o async,noatime,nodevmtime /
mount -u -o async,noatime /usr
atactl wd0 setidle 5

[wait a time]
# atactl wd0 checkpower
Current power status: Standby mode

I looked at smartctl but it doesn't look like I can set idle time  
with it, just readout status and perform self-tests.  Is there a way?

Thanks!

Brian