I'm wondering if it would be possible in Mojave to move the Users and Applications folders to separate HFS+ partitions without breakage? E.g. doing this or something similar:

  • Symlinking an app folder on a HFS+ volume directly to /Applications or to a subfolder of it
  • Symlinking a Users folder on a HFS+ volume directly to /Users
  • ...or just specify users' folders individually in system settings, pointing to a HFS+ volume

The goal is to minimize the surface area of APFS, which has proven to be too unreliable for me after I was forced to do two complete reinstalls of the OS in one week when APFS got corrupted -- twice -- and did not repair itself.

Reinstalling the OS is relatively quick compared to restoring from a time machine backup and redownloading lots of large apps, so I thought that if I could isolate most of my data onto HFS+ I would save time if for some reason I decide to upgrade from High Sierra to Mojave again. The next time APFS decides to make the entire volume inaccessible and the OS unbootable I would then only have to reinstall Mojave and link in the existing directories.

Related questions

Why is this question not a duplicate? This deals with Mojave, which is known to be unnecessarily picky about file systems.

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    I highly doubt your performance is due to APFS, but I’ll answer so you can test that yourself. The only part that might be still less tuned are fusion / HDD spinning rust drives as opposed to Apple grade and original SSD which have correct drivers on Mojave. – bmike Apr 13 '19 at 14:42
  • @bmike Thanks for your input and answer. I was all for APFS and meta data checksums, but it just printed the same checksum verification error on verbose boot over and over. One failed checksum seemingly results in being locked out of the entire volume, and I can't mount it in linux or do any investigation. Disk utility couldn't do anything about it. It worked great for six months, but from now on I just feel powerless with APFS. – Andreas Apr 13 '19 at 19:50

Consider that if APFS reports checksum errors, and you reformat and reinstall, and the same thing happens again after a short while - then you could very well have a failing storage medium.

Instead of relocating various folders to a partition formatted with HFS+, it would be wise to thoroughly check your drive for errors and possibly replace the drive.

  • I have considered it. It's a six months old 500 GB Samsung 860 EVO, and corruption occured after each of two forced shutdowns due to the OS locking up, i.e. there was no choice but to force a power cycle. I haven't come across any corruption test tools for SSDs, and I don't know how to determine the source of the corruption even if I hypothetically could inspect the data, so I currently don't know of a good way to determine whether it's a hardware problem. – Andreas Apr 14 '19 at 11:51
  • You can find free tools online. They work mainly by writing various to the disk and reading them back, noting any discrepancies found as errors. If the corruption occurred as you describe it, it could indicate a problematic SSD design. There has been problems earlier with cheaper SSDs that got their super capacitor rating wrong (or left it out completely). They could then acknowledge writes to the OS that were in reality not performed (or only partially performed) because they stopped writing too early when external power disappeared. Disks are meant to have they own power to do these writes. – jksoegaard Apr 14 '19 at 16:28
  • Ok, thanks, I'll keep a lookout for them. I found some older articles discussing the higher probability for corruption on power loss for SSDs, where I got the impression that only enterprise grade drives had power failure protection. If I understood you correctly even consumer grade SSDs should be expected to have some sort of protection today? I couldn't find a mention of it on the official page for my particular model though. – Andreas Apr 14 '19 at 19:27
  • Yes, I would certainly expect modern SSD drives to behave properly - or at least I would try to only use those that do. The sad thing is that there has been so many reports of very lacking quality in consumer SSD drives. For example the whole scandal around firmware default passwords and encrypted drives that were too easy to hack. – jksoegaard Apr 14 '19 at 19:57
  • If you can mention one of those free tools I'd be grateful. I could not seem to find any SSD data integrity tests myself. Lots of tools, but none that looked like they checked for corruption. – Andreas Apr 15 '19 at 13:15

The user home folder is very portable - you can place it anywhere - on network volumes even in many cases. Same with Applications - they write preferences to the main library, the main temp folder(s) and the user library, but they can exist anywhere you prefer in addition to the typical locations of the apps folder in the root and in the user home.

I’m skeptical you’ll see any benefit and might see less functionality and speed, but absolutely make a good backup and then start making other places to store files that let you learn or control things apart from APFS being the main container for everything added to the core system.

Nothing in Mojave changes the above - you may not be able to delete the default locations, but everything that isn’t SIP protected (all the apps you add later for instance) are highly portable.

You will struggle migtily if you move things the system wants in /Applications and each security patch and update will break as well since they depend on the locations being left alone for system apps and frameworks.

  • Really helpful to know, thanks. I might just consider un-downgrading to Mojave later and set this up. – Andreas Apr 13 '19 at 19:58
  • You can actually symlink and move the whole of /Applications too, you just need to turn off SIP. – Wowfunhappy Apr 13 '19 at 22:52
  • @Wowfunhappy Thanks, I think that I might have to do that. It looks like a pain otherwise; apps don't show up in launchpad unless they're individually symlinked to /Applications, and every installer gives me a shortcut to the wrong directory. It doesn't feel very thought through... – Andreas Apr 17 '19 at 11:11
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    @Andreas Note that I have no idea what Launchpad will do if you symlink /Applications. I don’t use Launchpad, I have an Applications folder in my Dock a la the Snow Leopard default... – Wowfunhappy Apr 17 '19 at 15:20

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