Server Fault is a question and answer site for system and network administrators. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

Is it possible to specify how many minutes of inactivity Mac OS should wait before it sleeps hard disks? Is there a plist I can manually specify "60 minutes" or something?

The GUI gives you the option to "Put the Hard disk(s) to sleep when possible" in the Energy Saver preference pane, but I'd like to have it wait longer.

share|improve this question
up vote 4 down vote accepted

To do it from the command line (and doesn't require the Developer Tools installed - available on any 10.4 or 10.5 system) you're looking for a utility called pmset (power management set).

disksleep - disk spindown timer; replaces 'spindown' argument in 10.4 (value in minutes, or 0 to disable)

eg. sudo pmset -a disksleep 60

As always for more check out the man page

share|improve this answer
Thanks - argh, that's correct too! If I could pick multiple correct answers, I would. – username May 16 '09 at 18:27
@Adam, sorry since this requires no optional install, and can easily be rolled out to clients via SSH, I do think it's the winning answer. – username May 16 '09 at 18:30
username - hey, glad you got the answer you wanted and hopefully mine will be useful to someone else who finds this page! – Adam May 16 '09 at 18:40

CHUD tools contains SpindownHD which does what you want - look in:

/Developer/Applications/Performance Tools/CHUD/Hardware Tools
share|improve this answer
+1 for the nice application icon :-) – splattne May 16 '09 at 18:24
Cool, that should do the trick - CHUD Tools is part of Apple Developer Tools, which ships with every Mac. Also, I got off my rear end and googled: There is indeed a .plist setting stored in the root Library: /Library/Preferences/SystemConfiguration/ – username May 16 '09 at 18:25
splattne - I think funky app icons are mandated as part of the Apple User Experience guidelines! – Adam May 16 '09 at 18:29

You could try SleepWatcher, an open source utility written by Bernhard Baehr, mentioned in this article:

SleepWatcher - A utility to run tasks on sleep/wake

share|improve this answer
It monitors sleep, wakeup and idleness of a Mac but (unless I'm missing something), SleepWatcher alone can not control sleep of a hard disk drive whilst the Mac is awake. – Graham Perrin Apr 1 '13 at 16:34

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.