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.

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

old books should also be read.

MacBook 13 inch White Unibody Core 2 Duo (Late 2009)
Machine Model: MacBook6,1
Family name: A1342
Model Number: MC207
EMC number: 2350
CPU speed: 2.26GHz

works like a charme!

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?