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For Apple hardware that ships with SSD only storage, will switching the file system from HFS+ to APFS prolong the life of an SSD drive?

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Will switching the file system from HFS+ to APFS prolong the life of an SSD drive?

No. APFS was optimized for flash (NAND) SSDs. In other words, it was designed to fully utilize the capabilities of an SSD to provide better performance. It wasn't implemented to prolong the life of an SSD.

In most respects, the life will be shortened. Why? Increased write operations for

  • Encryption
  • Snapshots
  • Metadata

None of that matters however, because based on the calculated life expectancy of an SSD, you will run out of capacity, long before it dies from usage. In other words, it's a moot point.

What other advantages/disadvantages it might bring?

This is entirely opinionated question. However, one thing to keep in mind is the initial premise of the answer - APFS was designed for SSDs. Meaning it wasn't designed for traditional spinning hard disks. Quite frankly, I've never upgraded a file system and thought "gee...this new feature is a disadvantage."

So, a better way to look at this is the advantages/disadvantages of running APFS on spinning disks versus SSDs.

For example, APFS on an SSD has encryption at it's core rather than another layer on top of the file system so, it's faster and more secure (advantage). On a spinning drive, this results in more read/writes on the physical media meaning slower performance, higher overhead, and shorter lifespan (disadvantage).

For an indepth look from a ZFS developers perspective, see this article

  • So, a potential side effect could be better performance? Apart from encryption, snapshots and metadata are there other use cases where better performance can be expected? I.e. copying/moving files? Better read/writes for small or big files? – ccpizza Nov 19 '17 at 11:24
  • That was the goal - better performance. Copy on Write means more data integrity. In 2014 (when APFS was conceived) we were very much aware of the exponential growth of both storage and file size so large file handling should (and was baked in). Handling small files is not an issue. When I say performance, it's performance of your app. Apple only cares about your experience using their products – Allan Nov 19 '17 at 11:37
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    I’ve edited this to avoid a general APFS discussion. Let’s spin off a second question if you want to delve into another area of APFS – bmike Nov 19 '17 at 11:54

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