User profile for user: carefulowner
carefulowner Author
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Interoperability of FAT32, ex-FAT, HFS+, APFS and NTFS

For some years now I've used a non-Fusion iMac (ie. an iMac with built-in fast flash-memory drive only) and, as part of my backup strategy for personal files, I use various USB drives - some pen-drives, some larger, portables - that I've formatted in some cases to FAT32 and, in others, to ex-FAT. Currently, this allows me to easily move my personal files between my iMac and a Windows machine that I still use occasionally. Ex-FAT, for instance, enables both reading and writing of USB drives between HFS+ (iMac) and the Windows machine (NTFS).


But I now want to get a 15-inch MacBook Pro (MBP), and unfortunately it appears that the MBP will not only come pre-loaded with High Sierra but also with the new Apple filesystem APFS. Any such new Mac will, it seems, be stuck with High Sierra as its initial OS. Nothing earlier, by way of an OS, is possible. The MBP will be all-flash and so, according to the Apple dictat, will have the APFS onboard; you can't have anything else.


So, okay, it's Hobson's Choice, but what now of the interoperability of my various USB pendrives and other portable drives? Will they all be usable with the new MBP? Having done some searches on 'APFS' in both these Apple Community forums and elsewhere on the Web, the news concerning the operability of various types of external portable drives with Macs that either come with APFS pre-loaded (such as the proposed purchase) or which have been upgraded to High Sierra isn't at all good; there are many reports of external all-flash (SSD) drives failing to be recognised by High Sierra when used as Time Machine (TM) backup drives for Macs that now run APFS. I've been planning to use a Samsung T5 external SSD as my TM drive for the new MBP, but lots of people with T5's and T3's are saying that the SSDs won't work with their APFS-equipped Macs.


What I'd like to know is, firstly, whether FAT32 USB drives have full read/write compatibility with APFS. Secondly, whether ex-FAT USB drives also have full read/write compatibility with it too (these drives would, of course, need connecting to the MBP via an adapter lead, since the new MBP has only Th3/USB-C ports). Thirdly, should I not bother to format the T5 drive to APFS but instead format it to HFS+ (OSX Extended Journaled) and, if so, is this going to make for possible malfunctions of TM (since, in both directions, converting from one filesystem to the other will be required, for each and every backup/restore operation)? It'd seem daft to, on the one hand be exploiting higher transfer speed to/from the T5 drive via Th3/USB-C, but then requiring the MBP to do an HFS+-to-APFS conversion (as it were) in one direction, and an APFS-to-HFS+ in the other direction.


To me, it remains unclear as to whether SSD drives like the Samsung T5 actually work as TM backup drives for Macs that run under APFS, and that APFS as a filesystem is far from bug-free, as yet.


Incidentally, a number of people using T5's (or T3's) have found - apparently, and I say that with due caution - that the following Terminal addition has enabled these drives to work with APFS:


diskutil list

(disk number for Samsung T5 needs noting)


diskutil partitionDisk /dev/disk# GPT JHFS+ New 0b


Then use Disk Utility (the GUI form) to convert the T5 to APFS.


I've no idea whether these people found it to be a longterm solution, though.


I realise that USB drive backed-up personal files (jpg, tif, pdf, doc, etc) themselves will always be interoperable across my various machines, but to retain full read/write capability, the different filesystems on these machines do have to be compatible. Also, why is Apple forcing us to use APFS on new Macs when it's quite clear that some external drives either can't then be used for TM backups or will require 'filesystem conversion' in both directions? I've already ordered a T5 (and they're not cheap!) but am holding off from buying the MBP until the news on these matters is more positive. In the meantime, I'd welcome forum members' views.

iMac (27-inch, Late 2013), OS X Mavericks (10.9.5)

Posted on Dec 13, 2017 8:10 AM

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19 replies
User profile for user: Phil0124
Phil0124
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Dec 13, 2017 2:37 PM in response to tbirdvet

The internal formatting of the drive has no relevance to whether the Mac or Pc can read an external one formatted differently.


i.e Macs can read and write to hfs+, fat32, exFAT, regardless of how the internal drive is formatted.


Macs cannot natively write to NTFS formatted drives, but can read from them.


Macs can only read and write to APFS formatted drives if they are running High Sierra (or Sierra, though not officially supported), whether the internal drive is formatted APFS or HFS+, it does not matter. Its the operating system that dictates what the Mac can read and write, not the format of the internal drive.


If you need to read and write to NTFS drives and volumes on a Mac, then you'll need an NTFS driver regardless of the format of the internal drive.


So any new Mac will continue to support hfs+, Fat32, and exFat drives and volumes natively regardless of what its internal drive is formatted as.

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User profile for user: Phil0124
Phil0124
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Dec 14, 2017 6:39 AM in response to carefulowner

carefulowner wrote:


So, for a brand new MacBook Pro supplied by Apple (the proposed acquisition), ex-FAT and FAT32-formatted pendrives will continue to function as before, this including, where relevant, usage of these pendrives also with a separate Windows machine. Thanks, that's reassuring.


Yes. It should work with fat32 and exfat formatted external drives and pen drives normally. "Should" being the operative word. As with all things there is no guarantee, but there is no reason to believe they will not work.


As mentioned, there are some bugs, but that is not an inherent lack of support due to APFS. I have a Mac Mini with an internal SSD drive that was formatted as APFS during the update to High Sierra, and all by external drives, and usb flash drives have continued to work.


Again, NTFS drives will require a driver such as Paragon, or Tuxera for the Mac to write to them.

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User profile for user: dialabrain
dialabrain
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Dec 14, 2017 4:43 AM in response to carefulowner

As Bob and Phil have stated, the fact that the internal drive is formatted as APFS has no relevance with external drives.


There is currently a Finder bug in High Sierra which won't allow files greater than 2GB to be copied to a FAT32 drive. They can still be copied using the Terminal or Finder replacements such as Path Finder. I'm sure the bug will be fixed in due course.

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User profile for user: dialabrain
dialabrain
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Dec 14, 2017 7:41 AM in response to tbirdvet

tbirdvet wrote:


Also if HS your internal drive happens to be formatted HFS (journaled) it will not recognize or read correctly any external drive formatted in APFS.

That's not the case for me. I have two iMacs with Fusion drives running High Sierra so no APFS. I've had no problems reading external APFS drives.


I also have a MacBook and a MacBook Air running High Sierra, both formatted as APFS, and haven't had any issues with external drives other than the 2GB limit Finder bug with FAT32.

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User profile for user: carefulowner
carefulowner Author
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Dec 14, 2017 4:15 AM in response to Phil0124

So, for a brand new MacBook Pro supplied by Apple (the proposed acquisition), ex-FAT and FAT32-formatted pendrives will continue to function as before, this including, where relevant, usage of these pendrives also with a separate Windows machine. Thanks, that's reassuring.


But, on that same point, you may be surprised (certainly, I was) to learn that, in a forum elsewhere, a respondent claimed most emphatically that "flash-based High Sierra machines don't recognise FAT32 USB sticks". So that, together with other instances of certain external drives apparently failing to work with APFS, began to sow some doubts into my mind. The respondent gave no further details, so unfortunately it's not known whether he/she got it plain wrong or whether maybe there was something not properly configured in his/her High Sierra system that made it so. I don't know about you but I find such unqualified, unresolved cases extremely annoying.


That said, there does appear to be some concern among Mac users that certain portable drives are - for whatever reason(s) - not recognised by High Sierra on Macs formatted to APFS. I've alluded to this in my initial posting, and tbirdvet has also mentioned it in his reply above. The Samsung T3/T5 Series portable drives are some that are affected, I gather. These Samsung flash-based drives have hitherto proved highly popular as Time Machine backup drives. They've been fast and reliable, and arguably class-leading. Online, I've ordered one of these Samsung drives (I've had them before and they've been excellent) and so that's why I've thought that it might be better to format it to HFS+, rather than to APFS.


I've no experience, as yet, of formatting anything to APFS but in the cases where certain portable drives have not been recognised by an APFS-formatted Mac, has it been confirmed whether the users had selected the correct instance of the external drive in Disk Utility (the whole drive, rather than, say, a partition), and whether the correct Partition Map (PM) had been used? I thought I read somewhere that GUID was not the appropriate PM to select and that formatting proceeded when instead Master Boot Record was chosen. But that might be just hearsay. I must admit it doesn't seem likely. Nevertheless, from what I read it seems that in High Sierra you may have to especially ensure that 'Show All Drives' is selected, as otherwise the external drive or partition may be permanently greyed out and unselectable.

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User profile for user: etresoft
etresoft
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Dec 14, 2017 4:47 AM in response to carefulowner

carefulowner wrote:


So, for a brand new MacBook Pro supplied by Apple (the proposed acquisition), ex-FAT and FAT32-formatted pendrives will continue to function as before, this including, where relevant, usage of these pendrives also with a separate Windows machine. Thanks, that's reassuring.

Hello carefulowner,

There is no change in the design of macOS with respect to external storage devices. That being said, every new version of macOS comes with a number of new bugs to deal with. High Sierra is particularly well-endowed in that aspect. Some of those reported bugs do involve external storage devices and some of those filesystems that you mentioned, such as FAT32. There is no way that anyone could predict whether or not a new machine will work with all of your existing devices. I can guarantee that it is supposed to work. I would not be surprised if you encountered problems. Such is life with Apple these days.

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User profile for user: carefulowner
carefulowner Author
User level: Level 1
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Dec 14, 2017 7:00 AM in response to Phil0124

Again, NTFS drives will require a driver such as Paragon, or Tuxera for the Mac to write to them.


But presumably if I get the APFS-formatted Mac to write a file to an ex-FAT USB pendrive, I can plug that pendrive into my Windows machine (formatted to NTFS) and the Windows machine will be able to read and copy off that file? Certainly, that's the case on my setup at present, with my iMac formatted to HFS+.

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User profile for user: Phil0124
Phil0124
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Dec 14, 2017 7:07 AM in response to carefulowner

carefulowner wrote:


Again, NTFS drives will require a driver such as Paragon, or Tuxera for the Mac to write to them.


But presumably if I get the APFS-formatted Mac to write a file to an ex-FAT USB pendrive, I can plug that pendrive into my Windows machine (formatted to NTFS) and the Windows machine will be able to read and copy off that file? Certainly, that's the case on my setup at present, with my iMac formatted to HFS+.

Yes. That should continue to be the case regardless of APFS.


Again the format of the internal drive whether Windows or Mac has no bearing on the formats it supports for external drives.

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User profile for user: tbirdvet
tbirdvet
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Dec 14, 2017 7:31 AM in response to Phil0124

I believe you did not understand my point. Running HS on the internal dive has caused some issues reading external drives initially and not sure why. I had 2 USB thumb drives both formatted Fat32. One read fine the other not recognized that was before using Sierra. I had to format it again using HS and then was working correctly. I also had an SD card with same issue. Others have reported similar issues.

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User profile for user: carefulowner
carefulowner Author
User level: Level 1
92 points

Dec 13, 2017 2:15 PM in response to BobTheFisherman

So then, FAT32, ex-FAT, and NTFS are all fully compatible with APFS, for both reading and writing? That's what you're saying. And perhaps you don't realise that, as far as the MBP is concerned, there is no 'previous'. Hmm, I'll need second opinions on what you claim is the case.


HFS+ is not fully compatible with Windows's NTFS; you cannot both read and write files between those two filesystems, that's why ex-FAT has to be used instead.

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Interoperability of FAT32, ex-FAT, HFS+, APFS and NTFS

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