Ever since the release of OS X 10.6.8, Apple has been selectively enabling the TRIM command for SSDs in OS X. This support continues on in Mac OS X Lion, as well as Mountain Lion, and even OS X Mavericks, but as many have noted, it only seems to work for Apple SSDs. Here’s how to enable TRIM across the board:
What is TRIM?
The TRIM command is an important disk command for SSDs that keeps your flash memory appropriately cycled so that you can achieve faster read and write speeds, as well as a longer lifespan for your SSD. As such, TRIM support is not the trivial matter that some make it out to be (although certain manufacturers, such as Other World Computing, include firmware that eliminates the need for OS-level TRIM support).
How to Enable TRIM Via the OS X Terminal (Recommended)
In you have an SSD that supports TRIM, follow the below instructions to enable it in OS X 10.6.8 or later. Note: This involves the use of terminal commands, so proceed at your own risk.
First, enter the command found in this document in the Terminal app on your Mac (found in Applications/Utilities).
After entering this command, you’ll need to enter a second command:
sudo touch /System/Library/Extensions/
The above-linked document also contains some troubleshooting instructions, as well as details on how to disable TRIM support if necessary.
Using a Third Party Tool
If you don’t find success using the Terminal command to enable TRIM for your SSD, there are two third-party apps that can help you enable TRIM support. I recommend trying Chameleon SSD Optimizer first. If that doesn’t do the trick, you can try TRIM Enabler 3.0 or later for Mac. I don’t like to recommend third-party tools, as they often make system-level changes above and beyond those performed by the terminal command – and that may not be in your best interest long-term.
Verifying TRIM Support
To ensure that the command was successful, and that TRIM really is enabled on your SSD, click the Finder menu in the Menu bar, then navigate to About This Mac > More Info > System Report. Then, scroll to the SATA/SATA Express section, and select your SSD. You should see a section called TRIM
Note: In some cases, a restart may be required before TRIM shows as Enabled in the System Profiler. With OS X Mavericks, not all SSDs will report TRIM support, but doing a benchmark both before and after the change should confirm that TRIM is functional.
Added Bonus: Thunderbolt TRIM Support!
As an added bonus in OS X Mountain Lion or later, including OS X Mavericks (I have not tested this in previous versions of OS X), raid can now also be enabled for SSDs hooked to your Mac through a Thunderbolt PCIe controller, such as the excellent Magma ExpressBox 3T! For more info on these devices, check out our complete review roundup of Thunderbolt PCIe controllers - perfect for Apple’s 2013 Mac Pro!
For more helpful tips, check out our full collection of tutorials by visiting our How-To category!
*Update: Revised on 11/6/2013 to reflect changes for OS X Mavericks, to fix errors, and to provide a more complete and comprehensive guide to enabling TRIM support.