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.
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"
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.
setpci -d 8086:2828 90.b=40
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?
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.