I'm planning on upgrading to Yosemite from Mavericks on a Mid-2010 MBP 15" with a Samsung 840 PRO drive as the primary drive. I have TRIM disabled! The process I want to use is as follows so I'm just looking for a validation please!

  1. Make sure Time Machine backup is current and good. I'll restore a single file to verify.

  2. Verify TRIM disabled via System Report. Shows "TRIM Support: No"

  3. Download installer from App Store and run upgrade in place.

  4. Once done, reboot.

If all is well:

  1. disable signed kernel extensions.

  2. Install TRIM Enabler

  3. Reboot

Should be done.

Are there any problems with this methodology that I should be aware of?

Is there a significant advantage to a clean install versus upgrade in place? I know there is for Windows, but I've upgraded this system twice now with no problems.

Thanks in advance for the advice.

  • I've never had an error upgrading with the Installer app with an upgrade. Then again, I don't have TRIM support enabled, or a SSD. Also, this may help you.
    – Spotlight
    Commented Jan 14, 2015 at 3:12
  • Just a warning: MBP 15 mid 2010 might be having a lot more GPU Panics. It's a known issue, but not all models have it. discussions.apple.com/thread/5759538 apple.stackexchange.com/questions/137181/…. My friend upgraded to Yosemite and since then He has ~3 crashes a day. Never had them before. Commented Jan 14, 2015 at 9:51
  • Small note: TRIM enabler will do the disabling of kexts for you. Also make sure that if you have TRIM enabler installed already (not clear from your question) that it says 'Patch is inactive' or whatever. I don't know if System Info always picks up on the change TRIM enabler has made (though it seems to have on my Macbook).
    – oarfish
    Commented Jan 14, 2015 at 10:06
  • I'm wondering if the kernel panics are related to the bad Nvidia chip on the motherboard? I had that problem and Apple replaced both the motherboard and the screen.
    – AlamedaDad
    Commented Jan 15, 2015 at 0:03
  • I don't have TRIM Enabler installed now. Frankly I didn't know about TRIM until the other day.
    – AlamedaDad
    Commented Jan 15, 2015 at 0:04

3 Answers 3


I never do upgrades any more - I made this from several times from Snow Leopard to MountainLion and my MacBook Pro 15" Dec 2010 got sloppier and sloppier in performance. Instead, I would recommend the following procedure which gets you a real fast Yosemite installation with a fresh and clean system:

  • Make a full backup with Time Machine
  • VERIFY the Backup of your most important data, not your applications! That means also a separate Backup of your Library folder!
  • Copy the most valued data onto another USB Drive for faster access.
  • Look for all the Yosemite updated drivers for your peripheral devices, like mice, headsets, special keyboards, USB video- and soundcards etc. Save the installers on the second USB Drive where you copied your most valued data on to. Do this also with your favourite OpenSource Software like Firefox, Chrome and your application installers etc.
  • Download the Yosemite installer.
  • Create an installation USB stick.
  • When booting from the USB stick running the installer, delete and format and re-partition your harddisk you want to install on.
  • Install Yosemite
  • After installation, configure your new system as you like it, play around with it to get acquainted.
  • Start installing drivers and tools and applications.
  • Start copying back your most valued data and your backed up
  • Have fun. :)

You will get a system exactly for your needs, without any old drivers/kext and you cleaned up in great detail. :)

My MBP Pro is now flying at high speed below radar... :)

  • Thank you for the note! I actually have 2 drives in my MBP. I replaced the SuperDrive with a new Hybrid HDD and all my data is on that. My concern is more the apps that I have. For instance I don't have the Office installer anymore. The FOSS stuff I can replace. Is is possible to restore the apps from backup or do I need to go find the installer somewhere. The rest of your comment makes perfect sense and I'd like to go that way. Thanks!
    – AlamedaDad
    Commented Jan 15, 2015 at 0:06

I think you are well read and good prepared.

The only thing that would bother me is the disable signed kernel extensions

the kext-signing setting is global, if you disable it you should be careful to only install system drivers from sources that you trust.

but if you know what you are facing go and doing dive in.


Your approach is dangerous and could result in a non-bootable system. See my answer here:

Since the release of 10.10.4, Apple now provides a new tool called trimforce, allowing users to activate TRIM also on unsupported disks. So now you can do:

sudo trimforce enable

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