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Should I use APFS on external SSD?
Optimized for all-flash storage, APFS features strong encryption, space sharing, fast directory sizing, and improved file system fundamentals. If you intend to use your external drive to move files between Macs running different OS versions, it is recommended that you format your drive in HFS+ instead.
Does High Sierra require APFS?
macOS High Sierra: Startup SSD volume must be APFS; other drives can wait. But it’s not backwards compatible with older versions of OS X or macOS. You’re required to upgrade any SSD startup volume when you install High Sierra—there’s no way to prevent it.
Why does APFS write to a different block?
In contrast, APFS writes changed data to a different block, and then marks the old block as no longer being in use. This doesn’t change the total number of erase cycles, but enables them to be spread more evenly over the SSD even when only a few files are very active.
What’s the name of the space manager in APFS?
Apple has still released very limited information about APFS, and its latest reference manual doesn’t mention TRIM at all, for instance. Two important sub-systems within APFS are its Space Manager (‘Spaceman’) and the Reaper. Spaceman is responsible for allocating and freeing blocks to store file system objects and file data.
Is the APFS file system good for wear levelling?
File systems designed for general use, or in the days when almost all writable storage was on magnetic media, usually don’t behave in a way that aids wear levelling. APFS has a feature which should improve wear levelling, though: copy on write.
How does an operating system help an SSD?
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 allows the SSD controller to erase that block, and maintains good write performance even under heavy use with limited free space.