Enable TRIM in OS X 10.7.5 to 10.9.5

os-x-enable-trim.md

Enable TRIM on non-Apple SSDs in OS X

NOTE: This is tested on the versions mentioned in the title, and NOT earlier or later versions. YMMV.

Run the following commands in Terminal…

Backup the original driver:

sudo cp /System/Library/Extensions/IOAHCIFamily.kext/Contents/PlugIns/IOAHCIBlockStorage.kext/Contents/MacOS/IOAHCIBlockStorage /System/Library/Extensions/IOAHCIFamily.kext/Contents/PlugIns/IOAHCIBlockStorage.kext/Contents/MacOS/IOAHCIBlockStorage-backup

Modify the driver (choose only one of the following lines, based on the version):

# 10.9.4 & 10.9.5
sudo perl -pi -e 's|(^\x00{1,20})[^\x00]{9}(\x00{1,20}\x54)|$1\x00\x00\x00\x00\x00\x00\x00\x00\x00$2|sg' /System/Library/Extensions/IOAHCIFamily.kext/Contents/PlugIns/IOAHCIBlockStorage.kext/Contents/MacOS/IOAHCIBlockStorage

# 10.8.3 to 10.9.3
sudo perl -pi -e 's|(\x52\x6F\x74\x61\x74\x69\x6F\x6E\x61\x6C\x00{1,20})[^\x00]{9}(\x00{1,20}\x54)|$1\x00\x00\x00\x00\x00\x00\x00\x00\x00$2|sg' /System/Library/Extensions/IOAHCIFamily.kext/Contents/PlugIns/IOAHCIBlockStorage.kext/Contents/MacOS/IOAHCIBlockStorage

# 10.7.5, 10.8.1, 10.8.2
sudo perl -pi -e 's|(\x52\x6F\x74\x61\x74\x69\x6F\x6E\x61\x6C\x00{1,20})[^\x00]{9}(\x00{1,20}\x4D)|$1\x00\x00\x00\x00\x00\x00\x00\x00\x00$2|sg' /System/Library/Extensions/IOAHCIFamily.kext/Contents/PlugIns/IOAHCIBlockStorage.kext/Contents/MacOS/IOAHCIBlockStorage

Run these commands in succession to clear the system caches to enable OS X to pick up the modified driver:

sudo kextcache -system-prelinked-kernel
sudo kextcache -system-caches
sudo touch /System/Library/Extensions/

Restart the Mac.

@RJVB You should be able to see it in System Information.app → Hardware → SATA → Trim Support: Yes

So does this only work for SATA disks, i.e. not via the SATSMART driver that provides SMART support for drives connected in other ways? Or, does the info just not show up there because of a limitation in the SysInfo app? Is there any other way to check if support is enabled, or if TRIM commands have actually been sent?

@RJVB I've only tested this on SATA SSDs, as this was the only way to get TRIM back in the day. (Later versions of OS X supported the trimforce command.) Sorry, I don't know of a way to check if TRIM is actually working at a lower level.

Do you know if it's supposed to work with external drives?

Thanks man. Worked on my evo860 SSD on my mid-2012 i5 on OSX 10.9.5 after the initial software update following reinstallation of OS X.

Hi there — Can confirm this code works on 2006 MacBook Pro 17" Core2Duo 3GB RAM with cheap Fanxiang S101 1TB SSD.

Had to paste into Terminal a couple of times, reboot, no joy in System Info — so tried final time but pasted all three of the second set all at once — rebooted again and System Info confirmed "Trim Enabled: Yes". Thank you so much! Very pleased.

Thanks for figuring this out.

P.S.: That's on Mac OS X 10.7.5. Lion (!). Works like a charm.

Do you know if it's supposed to work with external drives?

Still doesn't, not for me in any case.

So periodically I just take the ones I use to a Linux rig that has Paragon's ufsd driver installed. I checked with them: even with the free version their HFSx support is good enough that you can run fstrim on them safely.

On more recent macOS releases, there are other ways to enable TRIM, including external SSDs.

Check out this article: Will your new SSD support TRIM and SMART?