How to tell what is accessing the array?

I get the emails every so often during the day telling me the status of my unraid box.  Usually, all the disks in the array are spun down and the email tells me that.  However, every so often one or more of the drives are spun up.  And they shouldn't be.  There is no one at home or anything that I know of that should be doing anything on the computer.  So, I'm wondering if there is anything or any way to tell what is hitting the array.  I might have a virus on another computer on my network or something, so it would be nice to know what it was.  If nothing else, I'd rather minimize the times that the drives spin up and down, especially if it isn't for me to actually use it.

Thanks,

Chris