Latest OS X update allows you to enable TRIM for third-party SSDs

Pretty much every operating system in use these days supports TRIM—a special ATA command that the OS sends along to an SSD when deleting files on that SSD. The lone exception to that list has been Apple’s OS X, which—at least until today—only supported TRIM on its OEM SSDs. If you took a Mac that originally came with a spinning disk and installed an aftermarket SSD in it yourself, the operating system wouldn’t use TRIM on the disk—at least, not unless you resorted to third-party tools.

With today’s OS X 10.10.4 update, however, Apple has added a command line utility that can be used to enable TRIM on third-party SSDs without having to download and install anything. Called trimforce, the utility can be executed from the OS X terminal, and it requires a reboot to start working.

We’ve enabled it on a pair of older Macs in the Orbiting HQ with aftermarket SSDs in them, and so far we’ve had no issues—giant scary warning notwithstanding.

As we recently explained, even though modern SSDs generally have quite good garbage collection routines for keeping their unused areas ready to receive writes, TRIM helps SSDs out by telling SSDs which pages can be marked as stale when an operating system deletes files (something the SSD ordinarily would have no way of knowing). It’s by no means a requirement, but it’s helpful and could potentially help the performance of an SSD as it ages.

The scary warnings about trimforce are likely in place because not every disk implements TRIM in the same way, and older SSDs might behave oddly or in ways that OS X doesn’t expect when told to TRIM pages. If you have a relatively recent SSD, though, there shouldn’t be any problem enabling TRIM via trimforce—especially considering that same SSD in Windows or most current Linux distributions would already be using TRIM.