To TRIM or not to TRIM on OSX

well, here’s a question i bet a lot of you have come up with your own answers for. I would like to hear the official response from sandisk… do i use trim enabler on osx to use TRIM with your (awsome) ssd or not. 

the story goes that sandforce based controllers do not require trim and it can be detremental to their own garbage collection algorithms, so currently i am not using TRIM on my macbook pro. but since you guys are currently testing a firmware update that will work on the mac i figured its a perfect time for an official answer.

TRIM is suggested for best performance. Apple simply disables this for any third party SSD. I personally have configured my MAC to use TRIM and would suggest it. SanDisk most likely will not give an official statement to use TRIM on MAC because by default it is disabled by Apple. That said I use it and if you want to do a quick Google search and there are plenty of sites that explain how to enable it. 

Was thinking much the same myself, ive enabled trim now and i dont imagine ill notice anything to report back on.

i have been trying to find consensus on this point also. I believe its not a case of one size fits all for enabling TRIM on SSDs for OS X. OWC who have their own brand of SSDs specifically targettied for Mac users officially discourages the enabling of TRIM on OS X when using their brand of drives. This because the Sandforce controller that they use has its own garbage collection routines that negates the need for TRIM on the OS. 

I would like SanDisk to confirm if the controller in the Extreme supports background garbage collection. Because I am reluctant to make any unsupported mods to the OS unless I am very confident that there is clear evidence that its required. If there is BGC on these drives I wont be enabling TRIM on the OS, just as OWC recommends with their drives.

yes these drives support garbage collection. 

I have enabled Trim on my drive and all seems to be working fine. I see no reason not to enable this.

Until Intel releases a version of RST that supports TRIM in RAID modes,

TRIM will NOT function when 2 or more SSDs are members of a RAID array

controlled by RST device drivers.  TRIM reportedly only works on SSDs

configured in JBOD mode (Just a Bunch Of Disks).


I’ve had my doubts aswell… I read on an OWC forum that all SandForce from SF-2*** didn’t need TRIM enabled, since the controller already handled that stuff…

But what’s your performance? 

I have the Sandisk Extreme 240 GB (just got it, works like a charm) and made a clean install of Mountain Lion.

I’m getting about 270 MB/s write (too little, hmm…?) but around 500 MB/s read

And I’m guessing you are using something like BlackMagic to test the drives speeds? Read up on Sandforce controllers and compression. That write speed seems spot on for incompressible data such as used with a tool like BlackMagic.

Oh ok, yes, you’re spot on. Blackmagic was what i used.

Should i try other programs or does it look like it’s functioning optimally?

It’s sure as hell faster to boot from, that’s for sure.

My 7200 rpm stock drive (Hitachi, i think, 500GB) was just around 98 MB/sec for both read and write. (in Blackmagic)

It sounds like it is functioning perfectly, I personally wouldn’t bother with other benchmarking tools - they will only confirm what you already know. If you feel the need though, you could try something like xbench though it results will depend on the type of data each app uses for the test. Fully compressible data will yield a high write speed, incompressible data such as what BlackMagic uses will give your the lowest. A mixture of the two will give you a speed somewhere In between.

Here is what Sandisk Technical Support says about enabling trim on a Mac. I told them I had just installed an Extreme 480GB on a iMac.

"  Also we will not recommend you to enable TRIM on Mac operating system. TRIM and garbage collection are similar, but they are not the same thing. Unfortunately, for some reason, the Apple driver for TRIM seems to conflict with drives that have garbage collection built-in to the controller, so you won’t want to use it. It’ll actually decrease your drive’s performance. "

This answer  just seems to adds more confusion to the issue. Has anyone observed ( and measured ) a decrease in drive performance with trim enabled on a Mac ?


I have had trim enabled on my Extreme 240gb in my MacBook Pro for 6 months with no sign of any performance degradation. Also, trim is enabled by default on Mac SSD drives and a lot of them are Samsung 830 units. Unless they have a custom firmware that disables garbage collection, it would seem Trim and GC work together as designed by Apple. 

And to make things more confuse.

Here’ s Sandisk support answer to my question regarding Trim an Garbage Collection:

"  Please allow us to confirm that the garbage collection is part of the TRIM function; TRIM  needs to be active in order although Apple by default disables TRIM function for any third-party SSD, you can enable TRIM manually by editing the extensions or by downloading tools available online that will make the edit for you and will enable TRIM.

You may perform an online search regarding “Enabling TRIM on MAC”.   There are several resources available, however as they are not SanDisk resources we can take no responsibility for them."

Now what?!!

And the Sandisk Extreme uses a Sandforce controller(SF2281).

Here’s Sandforce take regarding Trim:

you are now at 2-1 in favor of Trim. :laughing:

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I would just like to chime in on this one because it seems there is a lot of confusion. TRIM will not have any ill affects on the SSD. TRIM and garbage collection essentially do the same thing. Both Erase unused blocks so they can be written to without the need to Erase it first. The difference between TRIM and garbage collection is that TRIM commands are sent by the host OS in real time where garbage collection is initiated by the SSD controller when there is no activity on the SSD. Both will work together to ensure the SSD maintains performance over the life of the SSD.

Exactly as drlucky says.