I've followed instructions to set the noatime flag in Lion so I can reduce SSD usage but it isn't working for me on Mountain Lion.

I'm still seeing this after restarting:

$ mount | grep " / "
/dev/disk0s2 on / (hfs, local, journaled)

Has anyone got any suggestions how to mount the startup drive with mount flag noatime?

  • What happens if you just run sudo mount -vuwo noatime / from the command line? It might produce an informative error message. Jul 28, 2012 at 21:07
  • it gives no error, output shows noatime is enabled but it only lasts until the next restart, so it needs to be scheduled I guess. Jul 29, 2012 at 12:06
  • 1
    Yeah, I knew it had to be scheduled. I asked because I wanted to know if it was the command that had failed. But as you found out, it was the scheduling that didn't work. Jul 29, 2012 at 13:24
  • It will work see my expanded answer > superuser.com/questions/487926/…
    – user35063
    Nov 20, 2012 at 18:20

4 Answers 4


Ok, I think I've got it working.

Add the file /Library/LaunchDaemons/com.nullvision.noatime.plist with contents:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" 
<plist version="1.0">

Run these:

  • sudo chown root:wheel /Library/LaunchDaemons/com.nullvision.noatime.plist
  • sudo chmod 644 /Library/LaunchDaemons/com.nullvision.noatime.plist
  • sudo launchctl load -w /Library/LaunchDaemons/com.nullvision.noatime.plist

The permissions have to be set to that for launchctl not to complain.

Then you've got this on restart:

$ mount | grep " / "
/dev/disk0s2 on / (hfs, local, journaled, noatime)

You can check if it runs by looking in the console:

29/07/12 2:55:45.334 PM sudo[978]:     Aram : TTY=ttys000 ; PWD=/Library/LaunchDaemons ; USER=root ; COMMAND=/bin/launchctl load -w /Library/LaunchDaemons/com.nullvision.noatime.plist
  • 1
    I think it's okay for you to accept your own answer. It won't give you any reputation, for obvious reason, but it marks the question as solved. Jul 29, 2012 at 10:12
  • says I have to wait till tomorrow, probably to ensure other answers are provided if the OP thinks they've got it when they don't Jul 29, 2012 at 12:04
  • A small note, BTW: This runs the command with the v flag, but that just turns on verbosity. Which is hardly useful in a launchd-controlled job. I don't think it will even find its way into a log file? Jul 29, 2012 at 13:26
  • Yeah it puts it in the console, see my update Jul 29, 2012 at 14:30
  • That console message is from sudo, run in your terminal. The output from the mount command run by launchd is what I was referring to. Does it show up too? Jul 29, 2012 at 16:01

The tool Chameleon SSD Optimizer will work for this and it also enables TRIM. I did a lot of research and most were directing to TRIM Enabler. Then, I read few but VERY good news about this one and opted for it as it seemed newer, more stable and with no or fewer bugs.

I installed did it on my iMac (2,5 GHz i5, 16GB Ram, OCZ Vertex3 120GB SSD [boot disk] + original 500GB HD) running OS X 10.7.5. Although it was already a nice fast machine, this made things feel even faster. I use my iMac for photo and video editing with Adobe Packages and everything's stable with this addition.


I was having this same problem in ML. I followed the instructions you linked to and kept getting the same result as you.

Davids-MacBook-Pro:~ davidsilver$ mount | grep " / "
/dev/disk0s2 on / (hfs, local, journaled)

However, Harald Hanche-Olsen's recommendation to run sudo mount -vuwo noatime / seemed to correct the problem.

Davids-MacBook-Pro:~ davidsilver$ mount | grep " / "
/dev/disk0s2 on / (hfs, local, journaled, noatime)
  • Ah! It worked but as I feared the flag is reset on restart. It seems the plist isn't getting executed at startup. You can apparently check for com.nullvision in the console if it runs. Jul 29, 2012 at 3:39
  • See my answer... Jul 29, 2012 at 5:03
  • I did as you said above, however I still get /dev/disk0s2 on / (hfs, local, journaled) Jul 29, 2012 at 21:00

I also had problems and had do to some additional steps

  • change the permission of /Library/LaunchDaemons to 777
  • copy an existant plist as com.nullvision.noatime.plist
  • edit it's content as mentioned above and save it
  • change the ownership and permission as mentioned above
  • run launchctl as mentioned above
  • change back the permission of /Library/LaunchDaemons to 755
  • reboot and check with mount | grep " / "
  • Do NOT recommend escalated privileges of 0777. Files in LaunchDaemons should never be higher than 0644. The ownership of the file (with group) would be: root:wheel (something you actually don't list, but strangely reference).
    – user10355
    Dec 21, 2013 at 11:25

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