How to Enable TRIM for 3rd Party SSDs on Mac

A Solid State Drive (or SSD) is largely considered the single best upgrade you can make to your computer. SSDs trump mechanical hard drives because they don’t have any moving parts. This increases their read/write speeds dramatically. With SSDs becoming more and more affordable, upgrading has never been easier.

So you’ve purchased an SSD, and you’ve cloned your existing hard drive. You’ve installed it into your computer, and everything boots up fine. Job is done, right? If you’re using a Mac, you have one more step, enabling TRIM.

Windows 7 and beyond has enabled TRIM for all SSDs; however, in Macs TRIM is only enabled on SSDs supplied by Apple. That means if you choose to upgrade your Mac with a third party solid state drive, TRIM will not be enabled, reducing the drive’s performance.

Before OS X 10.10.4, enabling TRIM required the user to disable security features from within the Mac OS. Nowadays Apple has included an official way to enable TRIM on third party SSDs, and all that is a required is a quick terminal command.

What Does TRIM Do?

Without getting too technical, SSDs write and delete data differently to mechanical hard drives. SSDs use flash memory, similar to RAM, only that SSD retains the data after it is powered down. SSDs store information in “blocks,” whereas hard drives store data to a magnetic plate. Because of this, hard drives can write information anywhere, but the plate needs to spin to the correct location first, slowing it down. SSDs on the other hand must find an empty block to write the data to. As your SSD fills up over time, this process become slower because less empty blocks are available, necessitating overwriting of data.

TRIM lets macOS know which blocks of data are no longer in use so they can be deleted. This means that when new data needs to be written to the drive, it can write to an empty block instead of overwriting existing data. This speeds up the write process as well as extending the lifespan of the SSD.

How to Enable TRIM?

Note: before augmenting the behavior of your OS, it is recommended to first back up your data!

Apple added a command called trimforce in OS X 10.10.4, allowing Mac owners using third party SSDs to enable TRIM.

1. Open a new Terminal window. You can do this by simply searching “terminal” in Spotlight or heading to “Applications -> Utilities -> Terminal.” With Terminal open, run the following command and hit Return:

sudo trimforce enable

Enter the administrator password when prompted. A disclaimer message will appear warning you of potential data loss and other scary things. Don’t get freaked out – this is Apple’s way of avoiding responsibility if something does go wrong. Hit “Y” to enable trimforce or hit “N” to back out. After you confirm your choice, your Mac will reboot. Once your Mac boots back up, TRIM will be enabled for all SSDs connected to your Mac.