I've researched soooo much.. I'm wondering why does my hard drive starts spinning/wakes up about every 10 minutes.. I use it for Time Machine and I also have some files stored in it. The hard drive is a WD 1tb My Book hooked thru firewire 800 but it happened with my LaCie 500gb that i got rid of last week. I have a 2.8ghz iMac, it happened on 10.5.6 and still happening on 10.5.7 Here's a list what I have done to try to avoid this issue.. 1. Gone under spotlight and add the Drive to the privacy section./Relaunch Spotlight. 2. Excluded the Volume from quicksilver. 3. Excluded the Disk from iStat pro on my widgets. 4.Put the Hard Disk(s) to sleep when possible. ENABLED! When I go to activity monitor I took a screenshot before and after the hard drive had waken up from sleeping.. The only thing that changed was the "Quick Look Server" process which i guess makes somewhat sense that it looks periodically for changes. If Quick Look is the problem I guess there's no way to fix the problem since there is NO WAY as far as i researched to exclude files from this program/app. My goal is for my external hdd to stay asleep for the whole hour waking up only for Time Machine.. I'm not expecting to get an answer for this issue.. is not a huge issue but i've read many people asking the question but no concrete answer... any ideas are welcomed.