Mojave: APFS on Fusion Drives

[ipedro]

APFS was announced for Fusion Drives in Mojave. However, beta testers have reported in early betas that Mojave doesn't use the SSD portion of their Fusion Drives, often running out of space at around 100GB. This is how APFS Fusion Drives behave on High Sierra, which doesn't officially support this feature. So, is this not yet implemented or are they still working through the issues that had the feature removed from High Sierra?

Has anybody noticed APFS on Fusion Drives working properly in the latest builds?

 

[macryan1]

Works fine for me, 2017 iMac 2TB Fusion. Startups are quick as is launching apps. No problems. Using about half of the capacity. Running Mojave 10.14 beta (18A365a)

 

[ipedro]

Thanks @MacRyan. I'm going to install Mojave then. It can't be any worse than the mess I've been running High Sierra with an unsupported APFS Fusion Drive.

 

[ipedro]

Well, looks like I have no choice now. After waiting almost a full year, running High Sierra with an APFS Fusion Drive and some ocasional bugs as a result, it finally gave in. What timing.

It was so messed up that I had to go into Terminal to merge the 2 separate drives into a single Fusion Drive. Fresh installing Mojave.

I’ll leave this here for anybody that might have had the same problem.

How did I get here? High Sierra supported APFS Fusion Drives in early betas. In fact, it insisted on it. I just never reverted back to HFS when Apple dropped support.

Looking forward to having a relatively stable iMac. Mojave — even in beta — is going to be a major improvement.
[doublepost=1534613455][/doublepost]... further adventures:

This came up...

Haha. Wow. Lion. I hadn’t seen that fabric background in a while (what’s up Forstall!). Eventually, I got it to boot up into my Mojave USB installer.

But it turns out High Sierra did quite the number to my Fusion Drive. Mojave insists that the drive has S.M.A.R.T. Errors and refuses to install on that drive. I know the drive is fine because Lion seemed to have no problem going ahead with the installation.

High Sierra messed up the tables and other sub structure on the drive.

Ultimately, I was able to fix the situation by converting to HFS and back to APFS which would rewrite all the tables. Mojave’s Disk Utility seems to have cleanly formatted a Fusion Drive into APFS and fixed the drive’s structure.

Mojave is installing (finally).

 

[oatman13]

Well, looks like I have no choice now. After waiting almost a full year, running High Sierra with an APFS Fusion Drive and some ocasional bugs as a result, it finally gave in. What timing.

It was so messed up that I had to go into Terminal to merge the 2 separate drives into a single Fusion Drive. Fresh installing Mojave.

I’ll leave this here for anybody that might have had the same problem.

How did I get here? High Sierra supported APFS Fusion Drives in early betas. In fact, it insisted on it. I just never reverted back to HFS when Apple dropped support.

Looking forward to having a relatively stable iMac. Mojave — even in beta — is going to be a major improvement.
[doublepost=1534613455][/doublepost]... further adventures:

This came up...

View attachment 776645

Haha. Wow. Lion. I hadn’t seen that fabric background in a while (what’s up Forstall!). Eventually, I got it to boot up into my Mojave USB installer.

But it turns out High Sierra did quite the number to my Fusion Drive. Mojave insists that the drive has S.M.A.R.T. Errors and refuses to install on that drive. I know the drive is fine because Lion seemed to have no problem going ahead with the installation.

High Sierra messed up the tables and other sub structure on the drive.

Ultimately, I was able to fix the situation by converting to HFS and back to APFS which would rewrite all the tables. Mojave’s Disk Utility seems to have cleanly formatted a Fusion Drive into APFS and fixed the drive’s structure.

Mojave is installing (finally).

Hi Pedro, I'd strongly advise using High Sierra's recovery environment to erase your fusion to HFS/CoreStorage. Let macOS Mojave installer convert you to APFS. If you use High Sierra's RecoveryOS to format your fusion drives as APFS, you're still in an unsupported state. You should use High Sierra's recovery environment to create your CoreStorage Fusion drive. The installer to Mojave will convert you to APFS correctly.

The link from support.apple.com you referenced is correct to get you back to CoreStorage. From there download the Mojave installer and let it convert you to APFS.

You don't want to use the High Sierra code to format your Fusion drive as APFS.

 

[ipedro]

Hi Pedro, I'd strongly advise using High Sierra's recovery environment to erase your fusion to HFS/CoreStorage. Let macOS Mojave installer convert you to APFS. If you use High Sierra's RecoveryOS to format your fusion drives as APFS, you're still in an unsupported state. You should use High Sierra's recovery environment to create your CoreStorage Fusion drive. The installer to Mojave will convert you to APFS correctly.

The link from support.apple.com you referenced is correct to get you back to CoreStorage. From there download the Mojave installer and let it convert you to APFS.

You don't want to use the High Sierra code to format your Fusion drive as APFS.

I ended up wiping my drive entirely using Mojave’s Disk Utility before installing Mojave.

Everything appears to be working well except for one nagging issue. The SSD portion of my Fusion Drive shows a S.M.A.R.T. warning. It’s listed as “unknown” and the drive appears to be working perfectly. I believe the APFS use in High Sierra must have tripped the S.M.A.R.T. Status and now it’s stuck in that state.

Nonetheless, I don’t store any critical files on the internal drive. Everything is on iCloud or on external RAIDs. If it fails, I won’t lose anything. I’d just love to be able to reset the S.M.A.R.T. status. Anyway to do it?

 

[oatman13]

I ended up wiping my drive entirely using Mojave’s Disk Utility before installing Mojave.

Everything appears to be working well except for one nagging issue. The SSD portion of my Fusion Drive shows a S.M.A.R.T. warning. It’s listed as “unknown” and the drive appears to be working perfectly. I believe the APFS use in High Sierra must have tripped the S.M.A.R.T. Status and now it’s stuck in that state.

Nonetheless, I don’t store any critical files on the internal drive. Everything is on iCloud or on external RAIDs. If it fails, I won’t lose anything. I’d just love to be able to reset the S.M.A.R.T. status. Anyway to do it?

S.M.A.R.T. information is directly received from the drive. So something on your internal drive's micro controller is reporting a failure. Either macOS Mojave is misinterpreting the data (which explains an Unknown failure) or there is an actual issue.

 

[Tarek]

@ipedro I still don't know how I feel about Apple dropping the OS X name for MacOS, but I can tell you I miss it after seeing that screenshot.