Blocks are usually defined during manufacture and are hard divisions-a hard disk drive’s 512-byte or 4Kbyte sector size is a block-level construction, set by the factory and programmed into the drive’s controller. The first is the hardware layer, or the 'block' layer. It comes down to the fact that even though SSD controllers are brilliant and getting better with every iteration, they still have no way of knowing what the operating system is doing.Īny modern storage device, be it an SSD or a hard disk drive or a flash-based USB stick, has two different 'layers' of internal organization. Today we're going to go through why you still get benefit from TRIM even on a modern SSD with super-efficient garbage collection. We have you covered if that’s what you’re looking for, though-just hit up this 10,000 word monster I wrote a couple of years ago if you want every single detail of what goes on inside those magical little devices. In this (relatively) short article, I'm going to explain why.įurther Reading Solid-state revolution: in-depth on how SSDs really workNow, this isn’t going to be an exhaustive look into how SSDs work. Here’s the skinny: TRIM is never a requirement, but it always helps, and you’re always better off with it than without it. This sparked a pretty big discussion in the comments on the ATA TRIM command, SSD garbage collection, and whether TRIM is even needed if your SSD has garbage collection. If your SSD’s controller has good onboard garbage collection algorithms, you should be fine even without TRIM. It was possible to work around this limitation in previous versions of OS X, but you can’t do it in Yosemite without opening up a security hole.

You should know that Apple doesn’t support TRIM (an operating-system-level garbage collection command) on third-party SSDs. In it, guest author Nathan Edwards issued this caveat about adding third-party solid-state disks to Macs: Last week, we ran a syndicated piece from The Wirecutter on what the best consumer-grade SSD is for most people to buy.

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