Lion does not allow disk sleep?

Background:

MacBook Pro 17" Early 2011 MC725LL/A

Mac OS X Lion 10.7.1

Lion OS is installed to SSD located in OptiBay.

Synopsis:

Lion OS prevents my HDD drive located in primary HDD slot from sleeping: HDD spins up every few minutes. I do not manually perform any operations that should have called the secondary HDD to spin.

I did the following to prevent my HDD from spinning:

- sudo mdutil -a -i off - to disable Spotlight searching and indexing of my HDD

- manually added my HDD to Privacy Spotlight list

- sudo pmset -a disksleep 1 - to limit spinning time to 1 minute

- Disabled/Enabled Sudden Motion Sensor

However, every few minutes HDD spins up and I have no clue what causes that. No iStat Menus, MenuMeters or similar software installed.

I have this behavior after I upgraded my Snow Leopard to Lion via Mac App Store, made a brand new installation of OS 10.7.0 and 10.7.1 from a flash pen drive.

Similar configuration under Snow Leopard works as expected: the HDD idles until I manually call files located on it.