Trim for Yosemite MAC


I just want to request that Sandisk make a firmware update for SSD Ultra II, that can support Trim on Yosemite (OSX).

I read that by an update that can be the solved.

I hope that can be release soon,

Thank you very much,

Kind Regards,

Apple is the one that disabled TRIM for SSD in Yosemite. Even the tools that enable TRIM in previous versions of the OS do not work in Yosemite. There are ways to make it work but you have to disable Kext signing. See the article linked below for some more info. 

all that said there is no update that sandisk can provide. Apple would require the SSD be qualified by Apple and they do not do any qualification on third party SSDs. 

In Dec 2014 I upgraded my MacBook Pro from a 250GB HDD to a 240GB SanDisk Ultra II SSD and installed Yosemite OS X 10.10.

Given that Yosemite disables support for TRIM for non Apple branded SSD drives.

What are the implications for using SanDisk drives with Yosemite OS X 10.10 and beyond?

Does it now mean I have to uninstall the non Apple branded Sandisk Ultra II?


No it does not mean that you need to uninstall your ssd drive that is none ffrom Apple but with the new great Yoshemite the authentication changed and so apple disables any 3d party software and even hardware if its detected.

In order to activate trim now you will need to do it manually and disable this option

more helpful information can be found here:

In response to deponia

I have been on a fast learning curve.

Thank you for the link, and I had already read it. Not sure how you could have knowledge of this link and tell me to I don’t have to uninstall my SSD.

The information contained on the link is clear as daylight. Currently the only way to enable Trim on non Apple OEM SSD drives running Yosemite is to disable kext-signing.

As the article says “……It is important to note that disabling the kext-signing to enable Trim is best described as taking a sledgehammer to crack a nut, and for most users it will not be worth it. “

Disabling kext-signing is not a path I want to go down.

Thus having no real choice, I uninstalled the 240GB SanDisk Ultra II SSD and reinstalled the original 250 GB Apple OEM Fujitsu HDD, but noticed the SATA interface running at 1.5 Gigabit. Then in an attempt to get the SATA interface to negotiate a Link Speed of 3 Gigabit I installed a 500GB Seagate ST95000325AS HDD –without success.

For the short time the 240GB SanDisk Ultra II SSD was in my Old MacBook Pro (13-inch, Mid 2009) 4 GB Mem, with a NVidia MCP79 ACHI it ran very well.

Reading the Apple forums there have been a number of issues with various SSD drives unable to negotiate a Link Speed of 3 Gigabit on this type of MacBook. A problem the 240GB SanDisk Ultra II SSD did not have.

With the 240GB SanDisk Ultra II SSD

  • The boot time 16 sec
  • Link Speed 3 Gigabit
  • Negotiated Link Speed 3 Gigabit

With the original 250GB Apple OEM Fujitsu HDD

  • The boot time 1 min 30 sec
  • Link Speed 3 Gigabit
  • Negotiated Link Speed 1.5 Gigabit

With a 500GB Seagate ST95000325AS

  • The boot 1min 20 sec
  • Link Speed 3 Gigabit
  • Negotiated Link Speed 1.5 Gigabit

It is bad enough that I had to downgrade fron SSD to a conventional HDD, but having the SATA interface running at 1.5 Gigabit on an Apple HDD defies belief.  It just goes to show that having Apple HDD is not a guarantee of trouble free environment.

For the moment Apple have halted my migration from Windows to OS X and that of HDD to SSD.


In that case where u dont like to disable the kext-signing in order to use the ssd normally with the mac book you do not have much of a choice but not to use a 3d party ssd with the mac.

Just to update…. I decided to downgrade from OS X 10.10 Yosemite to OS X 10.9 Mavericks on the Sandisk Ultra II SSD( a non Apple SSD) and install Chameleon SSD Optimizer to modify the all important Apple kext file. The Sandisk sata interface is negotiating at 3 Gigabit which is maximum interface speed supported by the 2009 MacBook Pro. The MacBook now runs significantly faster -not just at bootup, I have not seen a single spinning beach ball. While it is technically possible to install OS X 10.10 Yosemite on a non Apple SSD, kext signing has to be disabled for TRIM to be enabled. However in OS X 10.9 Mavericks the kext file only needs to be modified to enable TRIM. Now should you intentionally or accidentally reset the PRAM/NVRAM in OS X 10.10 Yosemite, your Mac will not boot. It sees that the kext file has been modified and will not load the driver. It is tricky to get the Mac working again if you are not IT savvy. Unless there is a compelling reason, use OS X 10.9 Mavericks and Chameleon/Trim-enable.

P.S I have written this post on the MacBook.

Just to update some more,  I posted this on another thread.

I have MacBook Pro 13-inch, Mid 2009. 2.53 GHz Core 2 Duo, 4GB Mem. Sata II (3 Gbit/s)

OS X 10.9.5 Mavericks with Chameleon to turn Trim on.

I have a 240GB SanDisk Ultra II (TLC), the drive is only a few months old.

Blackmagic Speed Test is reporting;

Write: 186 MB/s, Read: 262 MB/s with battery

Write: 208 MB/s, Read: 264 MB/s with power

Given the age of the MacBook Pro it only has a Sata II(3Gbit/S) host controller. The Blackmagic Speed Tests are an excellent result.