Checking whether disk is in sleep state (FreeNAS)

Question

How to check whether disk is in sleep?

I am doing some reports in background and, if disk is already sleeping, I would like to avoid waking it up. Which command can I use to check its status without waking it up?

Answer 1

atacontrol spindown [drive] should show the drive's current state and the timer.

Also, when the drives are spun down it will appear in the messages log, the most recent of which can be displayed with dmesg.

A side note, a drive's life deteriorate every time they change power states; minimizing power state transitions will prolong life.