Does Mac OS X Snow Leopard officially support SSD TRIM yet? If not, is there an expected availability? Also, is there a brand of SSD that is most compatible with a late-2009 Mac Pro?

3 Answers 3


TRIM is officially support with the latest build of 10.6 on Apple supplied SSDs only, i.e. not on an after-market SSD.

  • Is there a link to a support article for this? Jun 13, 2011 at 16:36
  • There was lots of stuff about it on macnn and macrumors when the last Air's came out.
    – Chopper3
    Jun 13, 2011 at 16:41
  • groths.org/?p=308. That said, it made performance worse on my garbage-collection enabled SSD.
    – churnd
    Jun 13, 2011 at 17:18

From Wikipedia, referencing this hack:

TRIM can be unofficially enabled on Mac OS X Snow Leopard by modifying extensions. Since February 2011 MacBook Pro models that ship with Intel SSDs are supported by Apple and feature TRIM support. Reinstalling the OS disables TRIM by default. It can be re-enabled by 3rd party software. By modifying extensions TRIM feature can be patched to support third-party SSDs and installed on other Macs

  • Thanks, but I was looking for official support from Apple. I've modified my question to reflect this. That hack looks very useful though! Jun 13, 2011 at 15:55

As stated, only Apple SSDs are supported.

However, to work around this restriction, you just need to zero out all instances of APPLE SSD inside the binary IOAHCIBlockStorage.

A command line solution is

cd /System/Library/Extensions/IOAHCIFamily.kext/Contents/PlugIns/IOAHCIBlockStorage.kext/Contents/MacOS/
sudo cp -pX IOAHCIBlockStorage ~IOAHCIBlockStorage
sudo perl -pi -e 's|\x41\x50\x50\x4c\x45\x20\x53\x53\x44|\x00\x00\x00\x00\x00\x00\x00\x00\x00|g' IOAHCIBlockStorage
sudo rm /System/Library/Caches/com.apple.kext.caches/Startup/Extensions.mkext
sudo touch /System/Library/Extensions/

Source: Keeping TRIM on Snow Leopard 10.6.8 Update

This worked perfectly on a Penryn 17" Macbook Pro with a WD Green 240 GB SSD, running OS X 10.6.8.

As an aside, I found that Trim Enabler 2.2, as advocated by this article, WORKING DOWNLOAD LINK for TRIM Enabler 2.2 for Mac OS X 10.6.8 Snow Leopard, did not work at all.

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