How to prevent the hard drive from spinning up?


macrumors member
Original poster
Jul 9, 2001
I'm running distributed projects (folding and seti) on a ram disk but still can't prevent the hard drive from spinning back up out of sleep. lsof in terminal has been overwhelming, and less than useful for tracking the culprit.

There must be some of you here in my situation. What have you done to keep the hard drive from spinning up occasionally? I don't think this activity is healthy for the drive.

-1.25 MDD
-No system sleep enabled
-Spin down HD when possible selected


macrumors 68020
Feb 3, 2004
Virginia Beach, VA
This is a really old thread to resurrect, but I was wondering if anyone had any ideas on the OP. I'm not even running folding on my iMac at the moment, but the hard drive keeps spinning up and then down over and over again. Anyone got an idea on trying to track down the culprit? I don't have any apps running that should require disk activity (that I can think of anyway).


macrumors newbie
Feb 3, 2009
not too old, we're going by 3's here, right?

i just found my harddrive spinning up sporadically, couldn't figure out for the life of me what it was doing. Activity monitor showed it peaking at the top of the graph. it even reflected reading and writing. not sure WHAT it was reading and writing (is there a way to find out?) so i came across this thread, saw folding at home, went into my sharing and sure enough i had Xgrid sharing enabled. so i disabled it and so far it seems to have solved the problem.

what is strange, however, is two things:
1) i thought xgrid shared unused processor or ram (not reading/writing to my disk)

2) i require a password for it... and nobody has my password (i set it up intending to mess with it one night then forgot)

so what gives? this is a very fresh install of leopard, (the newest OS X operating system generation, for my friends in the past,) so there is very little chance of a virus as i have not had any time to actually download anything.

i'll check back in 2012.


macrumors newbie
Feb 15, 2007
Time for the tri-annual thread update

I've been fighting to let my first-gen Drobo spin down, and some careful application of lsof and grep made it clear Spotlight (the mds process) was to blame for keeping it active.

Under Lion, however, it is not possible to prevent indexing of your Time Machine volume. This can be confusing, because attached external drives have a "volume" as a folder named Backups.backupdb, so though you can disable indexing for External Drive, it will still index External Drive/Backups.backupdb

If you try to add the drive to the Privacy panel of Spotlight preferences, it will be happy to let you. Only if you try to add that magic folder directly will it inform you that you are unable to. Similarly, if you use the command-line mdsutil tool, it will tell you indexing and searching is disabled on the drive volume, but only if you check or modify the settings of that nested folder will you see that it quietly ignores your attempt.

Hopefully now that I understand this, I can figure out a way to prevent this constant activity. But this weird coupling of backup indexing to Spotlight's process rather than Time Machine's is awkward and may finally compel me to use CrashPlan or Backblaze.
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