APFS disks and optimization... unnecessary?

Apple has been supporting HFS for decades and it has grown old and crufty with a lot of features grafted on over the years. Prior to it being journaled it was notorious to have data corruption. Apple knew they had to do something for the future. At one point, Apple was considering switching to ZFS from Sun Microsystems, now Oracle. ZFS was another entirely new file system which was rather revolutionary and scalable to a Zetabyte system in large server environments. There was some limited support for ZFS added to Mac OS X by 3rd parties and Apple was deep into working ZFS into Mac OS Server on internal non-public builds. A business decision was made to create their own file system instead of adopting ZFS. There might have been some licensing concerns and some technical issues.

Most of the useful features found in ZFS such as copy-on-write, data integrity, snapshots, etc. were implemented in APFS. While ZFS is not terribly optimized for SSD storage APFS definitely is.

1. Ability to save snapshots of the OS
2. Optimization for flash storage improves file transfer speeds and device longevity
3. Checksum values to file system metadata prevents and mitigates file corruption
4. Space sharing makes all partitions dynamic instead of static, allowing them to grow and shrink on the fly
5. Volume container encryption supports both single-key and multi-key encryption
6. Sparse file support allocates storage only when the user needs it, allowing users to create logical volumes larger than the physical volume containing them
7. Fast directory sizing quickly computes available space

Basically, APFS is a modern file system that takes care of all it's own maintenance so you do not have to worry about it. The operating system has built-in tools to repair APFS and Disk Utility runs the command line apfs_fsck repair tool. 3rd parties who write file system tools haven't really obtained the information necessary from Apple to build recovery tools that might go beyond Apple's built-in tools. They have to reverse engineer it for the most part. There are some data recovery 3rd parties but not many. Always backup any form of storage.

No, Disk Utility hasn't the capabilities of disk warrior especially when it came to revitalize a dead machine (if the problems where on disk, of course). I don't know if APFS is stronger than hfs+ in preventing these problems (it looks like) but I'd really love to have it working with apfs but I've lost faith on it.

Did hfs+ directories require optimization? Apparently, no. But Disk Warrior could identify unoptimized directories and fix them. But what Disk Warrior could do was rebuild broken directories in way Disk Utility couldn't and there was no need to re format a "broken" hd and reinstall everything from scratch. It helped me lots of times. GREAT APP!

No, it's not surprising that DW no longer functions. As mentioned above, the entire disk formatting scheme is new (APFS) and DW's tools just don't work any more. Kind of like trying to use SAE standard tools on a car with metric fasteners.

Just a word of caution in case you are using traditional hard drives ... and esp. if you use them for high-performance needs such as video editing or you need to preserve multiple copies and/or multiple versions of a file. APFS stores data very differently from HFS+ and was designed/optimized for SSD storage.

I suggest reading up on APFS cloning (aka copy on write), file enumeration and file data storage. These articles are decent starting points:

Copy, move and clone files in APFS, a primer

Using APFS On HDDs … And Why You Might Not Want To

An analysis of APFS enumeration performance on rotational hard drives

Just some cautionary information for anyone considering a wholesale leap into APFS on data drives.

DiskWarrior (versions 1 to 5) is awesome for HFS+. It saved many disks at our University over the years. But it does not work on APFS. APFS is much robust than HFS+, but still it would be great to have applications like DiskWarrior to rebuild its directory, just in case.

But unless Apple releases documentation and API for APFS (as available for HFS+), developers like Alsoft (DiskWarrior), Micromat (TechTool Pro) and Prosoft Engineering (Drive Genius) will not be able to release applications to rebuild the directory of APFS. So, it all depends on Apple. Time will tell.

Do APFS directories even require optimization?

No.

Those who used DW certainly swore by it. That said, I've been using Macs for 29 years and never needed it. But with apfs the question doesn't arise. There's a reason DW has not been updated...

johnnyjackhammer wrote:

Do APFS directories even require optimization?

Could not agree more.—Never used it, never needed it.

If it ain't broke don't fix it.