Mac News

How to activate TRIM on any SSD in MacOS10.6.7

First things first: This is experimental and we take no responsibility for what you do to your computer with these instructions.
With the release of the Lion Beta, the Mac OS now has support for TRIM use on SSDs.  TRIM allows SSDs to perform better by erasing unused data sectors ahead of time. 
However, some enterprising users have been able to get TRIM support on Mac OS 10.6.7
Hardmac was first to document the process, which we’ve pasted below.
Two things to start with:
— You will need an hex editor, you can find some easily for free. We used 0XED that we recommend, but there is also HexEdit and many others.
— Then you need to read the news about the activation of TRIM on an APPLE SSD, because the procedure is the same, the addition here is the modification of the extension.
You will need to modify the extension identifying the disk and thus allowing TRIM or not: IOAHCIFamily.kext version 2.05.
If you don’t have a 2011 MacBook Pro, you will have to download that version of the extension following the link in the news about the APPLE SSD. If you have a 2011 MacBook Pro, you can use the one you find in the extension folder, after checking that it is indeed version 2.05.
The owner of the extension folder is the root user, so you cannot edit the extension if you leave it in that folder. The easiest is to copy it in two different folders on the desktop one “original” to keep one extension as a backup in case you have a problem, and one “modified”. A simple click and drop will copy the extension.
Extensions are usually drivers allowing the system to work with the components connected or integrated to the computer. They can be quite complex.
Right click on IOAHCIFamily.kext and choose “Show package contents” you will find a plug-in folder in which there are two files, also extensions: IOAHCIBlockStorage.kext and IOAHCISerialATAPI.kext.
You can now access the file you have to modify: IOAHCIBlockStorage.kext/Contents/MacOS/IOAHCIBlockStorage.
To do so, do a right click again, on IOAHCIBlockStorage.kext and choose again “Show package contents” and follow the path until you reach “MacOS”. Keep that window open.
Launch your hex editor, click on File/Open and drop in the window that opens then the binary file IOAHCIBlockStorage. The main window of the software will open. Search for the following characters: “APPLE SSD”, be careful to include the upper case in the search. You will find two results.
You have to replace “APPLE SSD” by the name of your disk. You need the same number of characters (9), including spaces if there are some. The easiest way is to copy the first 9 character as they are displayed in System Profiler and to paste it in the right column in the hex editor. For example, you can see on the pictures that “OCZ-VERTE”, the name of our SSD, has replaced “APPLE SSD”. Do the same for the second result. Quit the editor and don’t forget to save of course.
From that point on, you just need to follow the directions explained in the other news about APPLE SSD. To make it short, you will have to replace the original extension by the modified one in the extension folder, but you have to do it right, follow the indications precisely.
If you have a problem during your first reboot with a stop sign (circle crossed), force the computer off, restart it while pressing shift, and it will boot without the extensions. Reboot again, it should solve the problem.
Here is the result we got:
Just a few more things to conclude:
Before trying to activate TRIM, make sure that your SSD supports it. The first models, even the ones that Apple shipped in 2008 do not support it.
TRIM is a command that was implemented very recently in Mac OS X, so it is still hard to tell whether is really makes a difference. Theoretically, this command prevents the disk from decreasing in performances while it is filling-up.
Also, we can only see that TRIM is marked as active in System Profiler, but we don’t have any proof that would allow us to say for sure that it is really active.
In the next few weeks, we will keep looking into and we will keep you updated on what we find.