![]() In practice, it shouldn’t be hard to detect poor write performance on an SSD which could be addressed by enabling TRIM. In early releases of APFS, users who manually enabled TRIM sometimes encountered longer boot times, which have been attributed to TRIM commands being sent to the SSD during the boot process. While generally available for software RAID systems, except AppleRAID, the TRIM command is normally not supported by hardware RAID systems.Įnabling TRIM doesn’t automatically improve performance, and in some circumstances can instead impair performance. Operating systems, including macOS, gained TRIM support around 2010, but this has proved quite complex and varied by type of SSD, and by file system. This allows the SSD controller to erase that block, and maintains good write performance even under heavy use with limited free space. To avoid incurring such overhead, the operating system can maintain a list of blocks which are no longer in use, and once a block becomes unused, it can inform the SSD’s firmware that the block can now be re-used. This is commonly addressed by relocating any other retained data within the block, so enabling that block to be erased ready to receive the new data. This is complicated by the fact that data is written in pages of 4-16 kB, but erase commands always affect complete blocks, which typically consist of 128-512 pages. However, before NAND flash memory cells used in SSDs can be re-used for writing, their contents must be erased, a process which makes writing to them significantly slower. When re-using those blocks for new files only requires that they are rewritten, as on a hard disk, that’s not a problem, as the disk controller can choose to reuse them whenever it wants without any side effects. On any storage medium, the file system normally deletes files by marking their storage blocks as being no longer in use. This isn’t an abbreviation, but refers to the TRIM command, which is central to this issue. As for power users, I recommend just buying a new Mac.With many Mac users switching from hard disk storage to SSDs, and following my recent article about adding a two-SSD external enclosure, I thought it might be useful to look at some commonly-raised issues about SSDs: TRIM, wear levelling, and how they interact (or don’t) with macOS, particularly APFS. ![]() This been said, I guess Apple would rather prefer to allow their Macs to support 3rd parties SSDs and have Macs secured, than have a lot of hacked Macs and all the internet taking about it.Īlthough, old Macs are getting obsolete due to the absence of current technologies, most of the regular users still can extract a bit more juice of their Macs, so they will find this tool very useful. I believe that Apple had made this decision because after the release of OS X Yosemite, which includes the new kext signing feature, Mac users were disabling this security feature, which when turned off, allows to execute arbitrary code in modified kext extension natively, WHICH was an huge security flaw. ![]() This is a huge win for the Mac users community because the people had ask for this a while ago. Yesterday, Apple had released OS X 10.10.4, including on it the new remarkable trimforce tool which allow native TRIM support for 3rd parties SSDs. Sudo kextcache -m /System/Library/Caches//Startup/Extensions.mkext /System/Library/Extensions # rebuild kext cache manually (could take a while) # looks for "Apple" string in HD kext, changes it to a wildcard match for anything # Important: Add "kext-dev-mode=1" as Kernel Arguments or the computer won't boot. Sudo cp /System/Library/Extensions/IOAHCIFamily.kext/Contents/PlugIns/IOAHCIBlockStorage.kext/Contents/MacOS/IOAHCIBlockStorage /System/Library/Extensions/IOAHCIFamily.kext/Contents/PlugIns/IOAHCIBlockStorage.kext/Contents/MacOS/IOAHCIBlockStorage.original # Yosemite: for recovering from stop sign on boot screen, please see # Looks for "Apple" string in HD kext, changes it to a wildcard match for anything # Update July 2014: no longer offline, see # Original version by Grant Parnell is offline () # just run "sudo trimforce enable" to activate the trim support from now on! # UPDATE for 10.10.4+: please consider this patch obsolete, as apple provides a tool called "trimforce" to enable trim support for 3rd party SSDs ![]()
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