When we had to reinstall Mac OS X on our MacBook Air (see news published earlier about Mac OS X 10.6.7), we lost the TRIM command on that computer, but we were able to activate it again. Here is how we did it, and since it worked perfectly with this model, it should work on all models of MacBook Pro running 10.6.7 or 10.6.7 using an APPLE SSD, except the very fist models that didn't support TRIM yet.
Before going further, here are a few important things:
- We didn't have time to test the TRIM command extensively. There is still a risk if you go on.
- You are about to modify extensions. Back-up your system in case you make a mistake that prevents a reboot.
- Don't try if you are not sure, it is safer to wait for Apple.
Now here is how to do it:
- Download and decompress the IOAHCIFamily.kext extension provided with the 2011 MacBook Pro.
- Go to the root of your hard drive, then in System/Library/Extensions and copy "IOAHCIFamily.kext" elsewhere in case you have to go back one step.
- Put the extension that is in your extension folder in the trash (you cannot put it elsewhere without copying it). You will have to enter your Administrator password to do that.
- Take the one you downloaded and put it in the extension folder. For that step too, your administrator password can be required.
- You now need to repair the authorizations on it. The easiest way to do that is to do Command-I on the extension folder.
Click on the lock to open it, type your password and then in the menu underneath, click on "Apply to enclosed items..." Then say yes to the warning coming-up. That way, you have given to the extension its rights necessary to make it work.
- Reboot and cross your finger, it might help even if we have often played with that extension with more or less results but without ever preventing a reboot.
If you followed the instructions and if you SSD supports TRIM, you will be happy to see that TRIM is supported, just like on the line highlighted in red.
As a reminder, TRIM will keep the writing performances of you SSD high. without it, the writing performances decrease rapidly, most notably for the data transfer rate.
[Update] Some members had problem when rebooting the system. We advise you, once you have made the manipulation, to launch Disk Utility to repair the disk permissions. If you get a circle crossed instead of the usual apple when rebooting, you can reboot without the extensions by pressing SHIFT during booting and you can then go back to the previous state.
We remind you that this manipulation will only activate TRIM on an APPLE SSD and no other.