hdparm UNmounted drive spins up

[wicked1]

I'm trying to get a couple of drives in my system to sleep and stay asleep. They have other OS's on them, and I have no need to ever access them from linux. They are not mounted. I run hdparm -Y on them, and they go to standby. about 10 min later I can check them (hdparm -C) and they are active/idle again.
What would cause an unmounted drive to spin up after being put to sleep?

[pallinger]

I have the same problem, just that the time to spin up is less then a minute, so hdparm -S10 never spins down for me. I do have a "spare" (not used by default) swap partition on the drive and some RAID spare partitions, but even after removing the spares from the RAID arrays and doing "swapoff -a", it still spins up later.
I am using ubuntu 9.04; maybe some magic hardware daemon is polling around every minute or so?

[pallinger]

It turned out that disabling the hddtemp daemon solved my problem partially. Now, the drive will spin down at "hdparm -S2 ..." and stay so until disturbed manually, but it will not ever spin down for "hdparm -S3 ...".
That is still a mistery to me, so if anyone has any suggestions why this happens, I would be glad to hear it...