powersaving of disks fails with activated raid...

Hi!

after I used a while single disks for storage and had no problems to suspend idle disks to save power-consumption, I switched soon to use raid5, but even the fs on it is not mounted and no md-monitoring in user-space is active, suspending fails due to activity on the disks below the raid5.

it seems, that the kthread of the raid is working on the disks even, there's no user-activity at all.

so my questions:

- what is the md-kthread doing there?
- is there any possibilty to prevent this behaviour?

if nobody knows an answer to that, maybe to this:

- is there a possibilty, how I can trace the raw disk-io of the sata-devices to see what is happening?

wiebittewas