Laptop: Hard drive wakes up every 5-10 seconds

[Michael Cronenworth]

Why would Linux be waking up every 5 to 10 seconds to write to the disk 
when I am sitting at my desktop or sitting at the login screen? (i.e. No 
programs running. Only 40 total wakeups seen in powertop)

- Seagate 320gig SATA
- XFS filesystem, relatime mount option enabled
- link_power_management_policy set to min_power
- vm.dirty_writeback_centisecs is set to 1500

I even unmounted /boot (default ext3) but that did not change anything. 
Every 5 to 10 seconds I see the HDD light flash and sometimes I hear a 
very faint "beeping" like the drive is waking up or powering off, 
whichever it is doing.

Thanks,
Michael