Apologize ahead of time for "resurrecting" an old thread, but I gotta say the Seagate 7200.3 drive (320GB, 7200rpm ST9320421AS) I am now using in my 13" MacBook Pro (2.26GHz, 4GB RAM) is a big FAIL.
While the read/write speeds are nice, this drive that's barely over a year old REFUSES to let my MBP go to sleep according to the Energy Saver settings. I've done all kinds of Terminal-fu to try to fix this; changed the SMS to 0, changed the "ttyskeepawake" to 0, reformatted the HDD *twice* using the Snow Leopard discs that came with my computer, uninstalled all apps that might be conflicting with sleep from the Applications folder (including all thrid party Preference Panes), ran a RAM test, ran Seagate's hardware test (all passed), repaired permissions, replaced the .plist file for Power Management, zapped the PRAM (I dunno HOW MANY TIMES now), tried an SMC reset (never could tell if that really happened or not on this unibody MBP), checked/unchecked the "put the HDD to sleep when possible," restarted umpteenth times, logged in as root/ran fsck, yeah...EVERYTHING. Even zeroed-out the HDD once when reformatting, still won't sleep. Passes the S.M.A.R.T. tests also. Cleaned all caches, etc. Nope. No sleep on its own.
The MBP still will NOT go to sleep on its own. I can close the lid, select Sleep from the Apple menu, and use the keyboard shortcut and sleep works fine. But leaving this MBP idle whether plugged in to power or on battery, it simply will NOT sleep.
Took it to the Apple Store, and the Genius said that the computer passed their hardware tests too; and that unless I put the stock HDD and stock RAM back in (both are gone; HDD is being used as a Time Machine backup for another Mac, RAM was sold), they won't replace my computer if there's a problem...which obviously there can't be, it passed both my and Apple's tests.
So it's gotta be the hard drive.
I ordered a Western Digital 500GB 5400rpm drive (WD Blue), and am going to clone things over and see if that solves the problem. I'm tired of all this reformatting. I can't possibly think of the problem being anything else. Gotta be the Seagate drive. I got it for Christmas, used it in a white MacBook 'til I upgraded this past Sept. '09.
So I'd advise AGAINST the 7200.3 drive. I'd hope Seagate has improved their 7200.4 or whatever 2.5" drive is their latest. This 7200.3 drive also drained the battery more as well, though I expected that.
Always been a WD fan, guess I should've stuck with them. I've never purchased another brand of HDD other than WD in the past...but I went on a recommendation from both a friend whom I respect and a podcaster who really liked his Seagate drives & thought I'd be ok. That was NOT the case. In my years as both a PeeCee and Mac "guy," I've never ran into a single issue with a Western Digital drive until now. Oh well, lesson learned. Never again, Seagate.
Unless anyone else out there has had this issue and can help me solve it...