After replacing the harddisk drive in MacBook Pro with a Solid State Disk I am wondering which settings I should change and how.

Thinking of things that are supposed to protect the SSD like

  • enabling TRIM support
  • disabling suspend to disk
  • disabling the shock sensor (if no standard harddrive is used anymore - does that make sense at all?)

Update: Swapping the harddrive with a SSD was just the best decision - totally different, much better experience, almost like a new, much faster MacBook Pro.

  • 1
    I have been using Trim enabler for the last few months. Other than that, I haven't changed anything... It would be interesting to have Trim Enabler be enabled automatically after an OS X update. If some kernel changes come with an upadte (e.h. minor OS X versions), the Trim Enabler patch will be disabled, usually.
    – Arne
    Dec 25, 2012 at 22:23

4 Answers 4


Here you are some major points:

  • Reinstall your Mountain Lion.

  • Don’t run benchmarks on your new SSD

    Benchmarks usually write a lot of data to the disk (to test the write speed), wearing it out. So it is the best way how you can ruin your SSD even before you start using it. Don’t do it.

  • Enable TRIM

    OS X supports TRIM only for Apple-supplied SSD’s. If you want to have TRIM enabled with 3-rd party SSD drives - download Trim enabler from this site. Very experienced users may want to enable trim manually not using above mentioned enabler, here is the tutorial how it can be done by the hand.

  • Turn off local Time Machine snapshots [laptops only]

    There is no GUI switch to turn these local backups off, but it can easily be done on the command line. Just start Terminal.app and execute the following command: sudo tmutil disablelocal if you want to back to original settings use sudo tmutil enablelocal command

  • Turn off hibernation [laptops only]

    OS X saves all the memory to disk when entering sleep mode.The more RAM you have, the more gigabytes it writes to the disk every time you close the lid/put it to sleep. You can disable this feature via sudo pmset -a hibernatemode 0 command

  • Set noatime flag

    OS X by default records last access time for every file. Every time you read a file, a write is made on the filesystem to record this action. There is no point in doing it and no side effects if you disable that by mounting the root filesystem with noatime flag set. You can read more about it here and here:

  • Move user home directories to HDD [SSD+HDD only]

    This is only useful if you have both SSD as well as HDD in your Mac. You can move all the content of /Users folder to the HDD and create symbolic link from the SSD to it by running this 3 commands: sudo ditto /Users /Volumes/your_hdd_name/Users sudo mv /Users /Users.bak sudo ln -s /Volumes/your_hdd_name/Users /Users

  • Turn off sudden motion sensor [no HDD only]

    If SSD is the only drive in your Mac, there is no point in using the Sudden Motion Sensor. You can turn it off by sudo pmset -a sms 0

  • Turn off hard drive sleep [no HDD only]

    Some websites mention SSD may freeze when the hard drive sleep feature is on, so it is recommended to turn it off. It can be done in the System Preferences->Power settings->Put hard disk to sleep.

The full article about above mentioned tweaks can be found here

  • 1
    are you sure that removing hibernation is a good idea ?
    – Render
    Dec 30, 2012 at 15:13
  • Similarly remove local Time Machine might not be a good idea. Your SSD will last for years don't be too worried about writing to it for standard OSX use
    – mmmmmm
    Jan 8, 2014 at 16:51

I installed a 256GB SSD into my first generation 17" unibody MacBook Pro a couple of years ago, before there was a third-party trim option. Since then, I've only gotten three speeding tickets for my computer being as fast or faster than the current machines.

The third-party SSD Trim Enabler has been the only change I've made to accommodate the SSD.

You may still want to keep the suspend to disk for hibernation ability. However, if your SSD is >really< small, disabling STD will free up drive space equivalent to the amount of RAM in your laptop.

I see no benefit from disabling the shock sensor.

Enjoy your much faster MBP!

  • Thanks, good point STD/hibernation/STD. About Trim Enabler - does this recover itself after OS updates? Dec 26, 2012 at 12:04
  • 1
    @greenforest Trim Enabler has persisted through some OS updates, not through others. Can't remember which. After updating I usually check the SSD Trim status and re-enable when needed. Bit of a pain, but worth the price of upgrading. Dec 26, 2012 at 16:48

Depends on what type of SSD you have. Some SSDs have a TRIM facility built into the firmware of the SSD — Sandforce controllers in particular have this. The Samsung 830 series have in-built garbage collection which renders TRIM unnecessary.

I have a Samsung 830 and have not modified a single thing. Runs great.


I've had a 240gb kingston sandforce-based SSD in my 2012 15" macbook pro for roughly 4 months now. i just installed a hard drive in the optical drive slot last week. I can confirm that the SSD occasionally takes up to 10 seconds to wake from sleep if the disk sleep option is enabled. since i disabled this option, this isn't a problem anymore. other than that i haven't changed any settings other than that (and moving my home folder the the HDD) and everything runs fine.

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