Why no APFS on Raids/Fusion Drives?

Can’t seem to find any discussion of this topic, so I thought to post it here. When 10.13 High Siera was released, there was a written kind of promise that APFS did work with RAID arrays. Now I realize I have a double whammy, my boot volume is a RAID 0 array of SSD drives. We KNOW that APFS can NOT be done on arrays. I have heard horror stories about some trying to update from Sierra on arrays to the point where I have NOT gone to High Sierra.

BUT this whole issue seems to have totally slipped under the rug, nobody, but nobody ever seems to want to talk about it, much less get some actual direction from Cupertino.


1 Like

Not sure what more info you are looking for. Those that converted their fusion drives to APFS were advised to convert them back to HFS+ before upgrading to High Sierra just before it was released, with a promise to support at some future date. There’s a KB article on this that I can dig out if you want me to.

At this time, there has been no hint of any progress on this issue. I’m sure they would have announced a solution if they had one now. They are still selling and heavily marketing fusions in several Mac models, so it’s obviously in their best interest to solve the issue or they will have to stop selling them.


My suspicion (and it is shared by many) is that APFS will never come to spinning drives and will probably not come to fusions drives, and if it does it will be an APFS SSD fused with an HFS+ rust drive.

The simple fact is that APFS isn’t done, and it proved harder to implement in the Mac world than anticipated. :frowning:

That seems even harder to pull off. If they don’t support spinning drives, my guess is they don’t bother with fusion drives either.

Thought I was clear… I want to know what is happening on a promise they made 2 years ago. As I said, I run SSDs for boot, but I do use spinning drives for Time Machine, a clone and my last system that ran Eudora (mostly because I have a TON of e-mail there and just 6 months ago I actually needed some information that was IN that Eudora archive… which I did find).

Now it may very well be true that they simply don’t have the right engineers to figure out how to do APFS on spinning drives, but then I’d ask why the hell did they go down this road in the first place. Did the start out to make a new file system that could NOT be used on billions of storage drives in the market? Did they start out saying that this fancy new file system was ONLY for SSDs and forget about any spinning drives? No, they said it was for all… then entered the cone of silence. They very easily could do a mea culpa and try and give at least a passable explanation why they are having issues, along with some kind of expected timetable.

I’ve been with the platform since May 1984, by 9/84 I had a 512k Mac with an internal 10MB hard drive. In all the ensuing years this has left THE sourest taste in my mouth!

This is the main reason I have NOT updated to High Sierra. I have a 2014 Mac Mini with a fusion drive… If I do update will all my drives remain HFS+ ??

I guess I’ll ask the question back: why does it matter whether the RAID drives are running APFS or HFS+? Is there a feature of APFS that you are hoping to use on the arrays? High Sierra will run as well on the HFS+ file system as it does on the APFS file system. It will mount and access drives of either format just fine, both at the same time, if you wish.

Apple doesn’t support APFS on Fusion drives, so if you update to High Sierra, it will not update the format of your drive to APFS. So that’s not a reason to worry.

And in fact, APFS is fine when running where it’s supported on SSDs. The only things that have had trouble are disk utilities, since Apple hasn’t published documentation yet.

1 Like

APFS has been on the Mac for much less than a year (Sep 2017). Right now, APFS on a rust drive is considerably slower than HFS+ and is, apparently, quite a bit more fragile as well. You do not want APFS on your spinning drive.

But it is really lovely on an SSD, and I am always very happy when a working copy of a 20GB movie file takes no time at all to create.

You were quite clear, but nobody here is going to be able to give you an answer and I strongly doubt that Apple would be willing to provide the information you seek. I don’t suppose you were able to get a ticket for WWDC18? That would be your best chance to ask Engineering. Otherwise, you’ll just have to read the proceedings like the rest of us, hoping for more.

The only thing I can add is that Apple put up the help wanted sign for engineers with expertise in this area and possibly related UEFI skills after HS was released, so they clearly didn’t have what they needed when they started testing before Sierra was released. I suspect they were lulled into complacency by the ease with which they were able to transition iOS to APFS and didn’t envision at the time that it would be that hard for macOS.

And to quote a different discussion:

“In total, Apple’s handsets, ranging from the budget-friendly iPhone SE to the expensive iPhone X, earned 90% of the industry’s profits during the fourth quarter.”

So where do you suppose apple applies the majority of their engineering assets?


Trust me Al, I AM painfully aware of that (last line)! Don’t like it much either. It’s just hard after SO many years being tied to an Apple desktop to see that my/our future being kinda bleak.

At least we can have a decent discussion here on TidBITS, I tell you it’s also very hard to see so much flat out ignorance exhibited by “Mac Fans” out in the general public.