Aftermarket SSD On A MacBook Pro: TRIM Gets Tested

By Achim Roos, Manuel Masiero
published

The ATA interface standard's TRIM command helps SSDs write faster and live longer. But if you own a Mac, you can only enable it with an OEM drive installed. A freeware tool turns TRIM on for aftermarket SSDs, and we take a look at how well it works.

TRIM On A Mac: Only For Apple's OEM SSDs

You already know that solid-state drives write data to 4 KB pages. In the process of relocating data, deleting stale data, and creating space for new data, they operate on larger blocks. This is what we refer to as garbage collection, and it's something that every SSD uses.

The trouble is that SSDs and operating systems typically don't have a very communicative relationship. When you delete a file, the OS marks the space consumed by that data as free, but doesn't tell the drive anything. Over time, you end up accumulating a lot of available space (according to the operating system) the SSD believes is still needed. It's only when an OS tells the drive to write to an address containing data that it figures out, "Ah, that information must be invalid." Up until then, those pages are still shuffled around by garbage collection, unnecessarily slowing down the SSD controller and wearing the drive's NAND cells prematurely.

This is where the TRIM command comes into play. When a file is deleted, the operating system sends a TRIM command to the SSD, marking those sectors as invalid data. At that point, the drive knows not to perform garbage collection on them.

Of course, support for TRIM comes from a few different places. The drive, controller, and operating system all need to be compatible. Fortunately, the process of building a TRIM-friendly ecosystem started a long time ago. Windows 7, Windows 8, Server 2008, Linux, OpenSolaris, FreeBSD, and OS X are all capable of the command. 

But just because a combination of hardware and software support TRIM doesn't mean it's always active. In the Windows world, we're fortunate enough that openness and compatibility are usually embraced. But Apple isn't so benevolent. It only allows TRIM to work on its OEM SSDs, and third-party drives installed aftermarket have this feature disabled.

The ways around this artificial limitation aren't secret. In fact, we showed you how to install a third-party SSD into a MacBook Air, turn TRIM on, and benchmark the drive in Upgrade And Benchmark Your 2012 MacBook Air's SSD. Today, we're showing you how to do the same thing using a different SSD and a different method, and then running another handful of tests.

Achim Roos
Achim Roos
13 Comments Comment from the forums
  • osamabinrobot
    i think you have an issue with your benchmark graphs, both trim enabled say fresh state
    Reply
  • osamabinrobot
    i think you have an issue with your benchmark graphs, both trim enabled say fresh state
    Reply
  • steamingabe
    Any chance you did any real world benchmarks with the stock 500gb drive as well as the 840 Pro?
    Reply
  • halcyon
    My hat is off to the author for the first 3 paragraphs, to say the least. I'm not sure where I've seen this more succinctly...more clearly explained.

    Ah, Apple. Why must it be a love-hate relationship? Clearly, you make some awesome hardware but your pricing and closed-mindedness is @$$munch. You disable TRIM if one doesn't pay 50 to 75% more for one of your lower-performing (than the typical aftermarket piece) OEM SSDs. Shame on you. Greedy bastards. Get with it or continue to decline. It's good to see in the case of TRIM Apple's @$$munchiness is so mindlessly circumvented. ...and to think I once gave them a bunch of my money. 4" Apple...4"
    Reply
  • crisso2face
    I wish it would be that easy. But its not. The problem with the OS X Trim command it that it kills your SSD. I fried 3 SSD Samsung 840 ( not the pro version ). Im at my 4-th right now ( thx God for warranty ). I work in a laptop store service. So I deal with a lot of laptops on a daily basis. This isn't my firs run in with SSD's. Cant really explain it, not an OS X expert. As soon as I turn on trim, with in a month or so, my SSD dies. This is my personal laptop. As I was saying, I work in a service, I have tech guys which are very good at what they do. If it were a motherboard problem, they would have found it. Its not the laptop ( MacBook Pro 17" Mid 2010 I5, nVidia 330M ). I can't really prove it, I my self, am a guy that needs hard proof, but this isn't a coincidence. 3 SSD's. I just recently had 2 customers with a macbook that asked me to upgrade to an SSD. They both came back to me in a month and a half with a fired SSD. After replacing them i hadn't turned on trim anymore. It's been 3 moths since, and they haven't returned since. Right now I myself use a 4-th SSD Samsung 840 without trim enabled. Haven't had a problem since. You do the math.
    Reply
  • ojas
    Hey, you know what i'd really like to see? How to enable TRIM/AHCI when you have a MacBook running Windows.

    I installed Windows directly, then performed some magic to install bootcamp drivers later, but the problem was that the EFI in Apple PCs disable AHCI when running Windows.

    Now Intel'ss SSD toolbox can still perform TRIM even when it's IDE mode (apparently) but i wasn't sure, so i had to Google a solution.

    Currently i have to enter four console commands in a GRUB menu before i can boot into Windows over AHCI, and BootCamp doesn't like it when i do.

    It's annoying, because i don't know much Linux, and i have no idea how to enable the GRUM menu or some sort of automated boot script that enters those commands for me.

    Commands:
    setpci -d 8086:2828 90.b=40
    set root=(hd0,1)
    chainloader +1
    boot
    Reply
  • ssdpro
    There is a big question here: Why does Apple intentionally disable TRIM on non-OEM drives? Think long term - why would Apple, who controls the testing/firmware on OEM storage, know they need to disable TRIM on all 3rd party drives? Are they preventing a problem that is exposed after long term usage of TRIM hacks with their EFI/SMC/OSX code?

    Look at crisso2faces comments above - I see that all the time on drives from multiple manufacturers, not just Samsung. Is seeing a couple extra MB/s in a benchmark worth gambling with possible catastrophic failure because you aren't using the system as designed?
    Reply
  • TheCapulet
    I agree with SSDPro. I know a lot of AppleCare Advisors, so I know first hand how terribly limited Apple Computers are. But the fact of the matter is... it simply comes down to this: If you want "advanced"(lol) features like TRIM support, don't buy an Apple computer.

    If you bought a Mac without doing research into your own required features, return it. If you're past your 15 days, look at it as a lesson learned. Macs aren't for everyone. Realistically, Macs aren't for anyone aside from people who want the most watered down experience possible, but the pro apps keep people in line for computers that don't really fit their needs.
    Reply
  • crisso2face
    The problem with trim on mac is that it has something to do with the comand it self that is sent from the OS X. From what I heard so far, it appears that the command is designed for a limited nr of drives. It has somthing to do with the timing and the blocks or cells of the SSD. The Trim comand of OS X is design for those specific drives. Repecing them with difrent 3rd party drives could prove catastrophic. I dont really understand how that works, up until now i bealived that the comand is basicly the same, no mater of the OS you use. As it turns out ( and i am not yet completely convinced of this ), the comand for trim is NOT the same for all OS's. Apparantly OS X tells the drive to do the trim in some different way, and that wers out the drive very very fast end eventually it dies out. Like I said. Im not an expert, but somthing obviously happens with the drives once you enable trim. Unfortunately I cant take the chance anymore.
    Reply
  • rojjr
    I am using a 256GB Samsung 830 Pro in a late 2011 iMac using TRIM enabler and I haven't had any problems in 8 months. Before I had this same drive in a 2009 iMac and it performed well also. *fingers crossed*
    Reply