TRIM (not actually an acronym) is a technology exclusive to SSDs that helps the drive erase data that is no longer in use. Traditional spinning disk HDDs do not actually erase all the data when you delete something. HDDs merely delete the file header(s) when you empty the trash. The file header is the information that points to the places where the actual data is stored. To save time (and wear and tear), a HDD will leave the real data on the drive to be simply overwritten in the future for something else.
SSDs, on the other hand, cannot overwrite existing data. The data first has to be deleted (written over with zeroes) before new data can be stored in the same location. This is fine for a while, but as the SSD fills up, it will eventually be stuck erasing lots of data before it can save new data. This will affect the performance of a SSD over time.
The way TRIM works is that it every time you delete something, the SSD zeroes out all of the data blocks that are associated with the files. This not only can make SSDs more secure out of the box, it also keeps the read and write speeds high over time!
Apple now includes a Terminal command that enables TRIM for third party SSDs. It’s called trimforce, and it works on OS X 10.10.4 Yosemite and higher and all versions of OS X El Capitan. It also is fully compatible with every Crucial SSD that Small Dog sells! After installing an SSD in your 10.10.4 or newer Mac, enable TRIM support with the following steps:
- Open Terminal (can be found in the Utilities folder)
- Type “sudo trimforce enable” (without the quotes)
- Type “y” (sans quotes) to agree with the warning
- Type your admin password (no letters will show up while typing)
- Wait for your Mac to restart
To check that TRIM is successfully enabled, click the Apple in the upper left-hand corner, click About This Mac > System Report. Choose SATA/SATA Express from the sidebar. You should see Crucial (or your brand of SSD) written somewhere there, and under that it should say TRIM Support with a Yes across from it. You have now unlocked the full potential of your new SSD!