Is APFS compulsory, going from Sierra to Mojave?

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Is APFS compulsory, going from Sierra to Mojave?

I've in the last few days completed a macOS upgrade I've had on the cards for quite a while - Mavericks to Sierra. It was a 'clean install' method I used. But now that I've a nice new edition of macOS running on my iMac, various fundamental questions are arising, particularly with regard to any further macOS upgrading that I do. For instance, in say a few months time I'd like to upgrade to Mojave.

Now, I seem to recall there being somewhat unresolved debate amongst Mac'ers concerning whether to swap to the APFS file system or instead to stay with HFS+ when moving from Sierra to either H. Sierra or Mojave? I vaguely recall that, in the end, someone suggested that that would depend not just on personal choice but on whether the Mac was using an all-flash drive.

My own iMac, though a late-2013 model, does use solely a flash drive; when I bought the Mac I opted for customisation. So, if I move from Sierra to Mojave, will the upgrade process automatically convert my Mac's drive (1TB) to use APFS? Will I have any say in the matter?

If the basic answer to this is yes, automatic conversion to APFS will take place regardless, will I then need to re-format all my external drives too, or will those external drives, which are currently formatted as a mix of HFS+ and ex-FAT volumes, simply communicate with the Mac more slowly (due to their file-system differences with that of the Mac)? In that scenario, would I be better off re-formatting almost all of the external drives to APFS?

What about the external drive that I currently use for Time Machine? Ideally, would that need to be formatted to APFS as well? If, as Mac users, we're being encouraged to gradually move toward universal take-up of APFS, does it make any sense to not reformat the TM drive to APFS? (Of course, that'd entail losing all current backups, or at least I presume so).

Nearly all my external drives are partitioned into separate volumes. With macOS, is it possible to have, on a given physical external drive, volumes or partitions where the file systems are different? That's to say, on a given physical drive, can one partition use the APFS filesystem and another partition use HFS+?

Posted on Jan 28, 2019 7:15 AM

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Answer 1

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MrHoffman

Level 10

148,833 points

Jan 28, 2019 10:32 AM in response to carefulowner

The APFS conversions are either performed manually, or are performed as part of installing macOS onto the specified target storage device. APFS conversions do not automatically occur to storage devices that macOS is not installed on.

While it's clearly the path Apple is taking for macOS and iOS, no, APFS conversion on macOS is not compulsory.

There is a command that can suppress the APFS conversion available.

As for your Time Machine backup devices, Time Machine on Mojave cannot back up to APFS volumes. I suspect we'll see some changes in related areas some unspecified future release of macOS, but I'm not aware of any Apple announcements here.

What Apple states: Prepare for APFS in macOS High Sierra - Apple Support

In addition to how High Sierra converted the target SSD, Mojave installations on other devices will convert to APFS.

It remains possible to have mixed file systems in separate partitions on a GPT GUID partition table device. Wouldn't be feasible to use Microsoft Windows with Boot Camp, otherwise.

Related Reading:

https://developer.apple.com/documentation/foundation/file_system/about_apple_file_system

https://developer.apple.com/support/apple-file-system/Apple-File-System-Reference.pdf

Pragmatically, I'd let the Apple defaults apply and let the automatic conversions occur, unless I had good and specific reasons to the contrary. Which means systems are drifting toward and onto APFS, as macOS upgrades and Mac replacements occur over time. And it means having good backups, but that's no different than the usual and longstanding recommendations.

There have and likely always will be unresolved debates, strongly-held opinions, trolling, clickbait and other dreck. I've found that cutting back on reading and following the Apple echo chamber really helps here, too.

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Answer 2

kahjot

Level 4

2,469 points

Jan 28, 2019 10:33 AM in response to carefulowner

Mojave will force the conversion to APFS down your throat. There are enough reported issues with Mojave and enough questions about APFS that you would be better off waiting for the kinks to be worked out before you install it. You do not need to convert and should not convert your other attached drives.

You might want to check out the extensive discussion of Mojave and APFS at Macintouch:

https://www.macintouch.com/index.html

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Answer 3

DonH49

Level 6

16,716 points

Jan 28, 2019 10:10 AM in response to carefulowner

good questions but you are making too much of the effect of ONE INTERNAL SSD drive will be automatic APFS. The only consideration will be any operating system prior to Sierra will not see the drive on the Desktop. All the way back to Yosemite Disk Utility will see it . I do not recommend using El Capitan or Sierra Disk Utility on an APFS drive but yes for Yosemite. Only if you need to get back to HFS+. A big consideration is the learning curve on disk Utility; you best do some research and brush up on it. That's why I kept Yosemite around to bail my learning curve out. Nowadays I don't need it any longer.

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Answer 4

Jan 29, 2019 4:19 AM in response to carefulowner

Very considered and informative question and answers here.

The only thing I would add here is about using Office 365 2019 with OneDrive.

Note that the new files on Demand feature for OneDrive is only available for Mojave onwards.

OneDrive 18.140x is the officially released version with files on Demand.

There is also standalone version 19.002x

If you are using OneDrive then I would recommend using this feature as it can consume a lot of local storage otherwise.

In addition, our experience with OneDrive with larger amounts of data is that it can consume large amounts of memory resources as it tries to keep up with synching the changes. Files on demand seems to resolve this somewhat.

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Answer 5

carefulowner Author

Level 1

92 points

Jan 29, 2019 3:55 AM in response to kahjot

Thanks everyone for your various inputs on this.

I've followed up most of the links quoted in the replies and it does indeed look as though APFS is compulsory if the Mac is one that uses an all-flash internal SSD.

Given that I'm now on macOS Sierra, my only upward path from hereon in would be to go to High Sierra and then, after that, Mojave. Or I could go straight to Mojave. Clearly, the straight-to-Mojave move would involve the least amount of messing around - or at least, it'd appear so.

Actually, I'm not planning to rush into a further upgrade, now that I've accomplished Sierra. However, some of the current uncertainties about Mojave are causing me to perhaps hold back from installing a fresh 2019 edition of Office for Mac on my machine. As far as I can gather, Office for Mac 2019 is installable optionally as 64-bit and is APFS-compatible as well as HFS+ -compatible, so in theory should be fine for all three of Sierra, High Sierra, and Mojave. I might just take a chance and put Office 2019 on Sierra right now and then wait some six months, say, for the position vis à vis Mojave to evolve and level out before upgrading macOS to Mojave. I'm assuming that because Office 2019 is 64-bit and APFS-compatible, it shouldn't get screwed up when eventually I do that upgrade (using the straighforward download from the Web method) to Mojave.

Meanwhile, on the basic matter of APFS, these are my conclusions, gathered from yourselves and from Apple's recent guides on the Web to which I've been pointed:-

For my particular Mac, which uses wholly flash drive, let macOS change the filesystem on the internal drive to APFS, when going from Sierra to either H. Sierra or to Mojave. This will happen automatically anyway.
Any external TM volume that's attached to the Mac and which currently uses HFS+ will automatically remain untouched in this regard by the further macOS install, and this is best left 'as is', ie. the TM volume is best left as HFS+ (Mac OS Extended Journaled).
All other external volumes should be left as HFS+ (or left as FAT-formatted, including ex-FAT, if specifically in use currently). My assumption is that there will be read and write compatibility of FAT and ex-FAT with APFS, both ways.

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Answer 6

MrHoffman

Level 10

148,833 points

Jan 29, 2019 7:51 AM in response to carefulowner

1: By default, yes. The HFS+ to APFS conversion happens automatically on High Sierra and later on SSD devices when macOS is installed on the device. You can avoid the APFS conversion using the install-time commands linked previously. It'll get tougher to maintain this configuration going forward as HFS+ is retired, though.

2: All not-macOS-boot-device volumes are untouched.

3: I'd look to use APFS going forward, unless there are specific reasons not to. Time Machine usage and volumes used for data interchange are salient examples of volumes that should not be converted to APFS.

Office for Mac 2019 works fine, as does Office 2016. Older Office versions have fallen off of support, and variously doesn't work. Some of the older Office versions have some nasty security problems, too. There's a good diagram of the Microsoft Office support included on the Office Wikipedia page.

Printers routinely fall off support from their vendors, and printers that require host-based driver packages and particularly host-based rendering tend to have short lifetimes. Printers with embedded LPR/LPD and telnet support, and with the HP raw port, and now with IPP support have longer lifetimes, as those can be configured using existing CUPS support and don't require printer-vendor-provided host-based drivers.

I'm running a mix of High Sierra and Mojave and iOS 12 on the various devices I deal with, and the biggest issue with various folks I deal with around Mojave has been the retirement of macOS Server.app and its replacement with an MDM package. That, and the folks that haven't updated older versions of Server.app in far too long. The T2 has caused a few wrinkles, too. But APFS has been an utter non-issue.

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Is APFS compulsory, going from Sierra to Mojave?

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