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. If you plan to run a lot of older programs that don't have 64-bit versions, then High Sierra is probably the right choice.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. If you're an iPhone or iPad user, then you may want to consider Mojave for the increased compatibility with iOS. Should I upgrade from High Sierra to Mojave? If you're a fan of dark mode, then you may well want to upgrade to Mojave. Apple considers Mac 'vintage' if they were released between 5 and 7 years ago, and obsolete if older than 7 years. Your Mac was released more than 7 years ago. While you can still use a Mac that can't update to Monterey, not being able to update is a sign that your Mac is aging into obsolescence. Comme pour Mac OS Sierra, la compatibilité nécessite un Mac datant de fin 2009. Il peut être téléchargé depuis le Mac App Store ainsi qu'un fichier d'installation. Mac OS High Sierra est-il encore disponible ? Mac OS High Sierra est toujours disponible au téléchargement.

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