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(There’s a big wide Internet out there that will guide you if you want to pursue this course.Apple macOS enables Trim for internal Apple SSDs only. Because I think it’s a terrible idea to disable this security measure I won’t provide you with the steps necessary to make it happen. And when you do, this opens the security hole that Apple has attempted to close. Instead, you have to turn it off globally. Unfortunately, you can’t do this on an extension-by-extension basis. The only way to allow TRIM to work with third-party drives under Yosemite is to disable kext signing. Without it, you can boot from the SSD but it won’t run with the benefit of TRIM. In cases where you have such a modified extension installed, your Mac won’t be able to boot from the drive. If Yosemite encounters such a modified kext file, it won’t run. The workarounds that allow TRIM to function with third-party SSDs require that kext files are modified. With Yosemite, kernel extension ( kext) files must be “signed” (or approved) by Apple for security reasons. This worked perfectly well with Mavericks. Instead, you’d do some Terminal work or use a third-party tool such as Cindori Software’s Trim Enabler to make TRIM work with your drive. However, if you’ve installed a third-party SSD, that drive doesn’t use TRIM because Apple’s TRIM technology is not built to support it. If you purchase a Mac with an SSD or Fusion drive built in, the TRIM technology is working away in the background to keep your drive running at its peak. In sum, the two technologies speed up the drive’s performance so that it’s not performing a lot of needless move and erase actions. Invalid data is erased when the drive is otherwise idle. TRIM works at the operating system level and ensures that only the good data is moved. The controllers within SSDs have a technology called “garbage collection” that moves the data within pages-both the good and invalid data-to new blocks and then erases the old ones. This takes time and slows down the drive’s performance. So if you have a block where half the data is good and half invalid, you have to move the good data to another location before you can erase the block. The difficulty is that the drive can’t erase individual pages. When the drive can’t find any remaining open pages, it looks for the pages that contain invalid data to erase to make room for the fresh stuff. Rather, a reference to it is removed from the LBA and it’s marked as invalid data. When you delete information from an SSD, that information isn’t really deleted. This is a kind of map that details which pages and blocks are and aren’t occupied with “good” data. The SSD uses something called Logical Block Addressing (LBA) to keep track of which pages and blocks have information on them. Let’s start with some words of explanation.Īn SSD writes small bits data to “pages,” and multiple pages make up blocks.

Should I hold off and what does this mean in the long run? I have installed third-party SSD drives (in my case Samsung) and until I saw the article was thinking about updating from Mavericks. I just read an article that Apple is disabling the TRIM function for third-party SSDs in the Yosemite OS update. Reader Richard Spitzer is concerned about using a third-party SSD drive with his Mac running Yosemite.