Inside macOS 10.13 High Sierra: APFS benefits end users with space, speed

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in macOS
Apple's next-generation APFS has made its way to macOS High Sierra after an official debut on iOS 10.3, and with it comes essentially instant file copies, better efficiency for greater overall speed, and fine-tuning of read and write operations boosting system performance.




There are a lot of "under the hood" changes in APFS, many of which will not be immediately apparent to users. In this first look at APFS implementation in High Sierra, AppleInsider examines the most obvious changes to users -- boot times, file copies, and storage efficiency.

Test platforms

For the APFS testing, we are using a 2015 i7 Retina MacBook Pro, and a 2012 quad-core i7 Mac mini with SSD. Both have 16GB of RAM.

Prior to installation, both machines were running 10.12 Sierra. The MacBook Pro needed a re-install of High Sierra after the machine's EFI partition was corrupted for reasons unknown -- but it hasn't happened since.

Boot times

APFS was previously restricted to non-boot devices. With High Sierra, that limitation has been lifted.

Prior to installation, the PCI-E SSD on the MacBook Pro booted in about 24 seconds from a shut-down machine. Following installation, the boot time from "cold iron" was cut to 18 seconds -- 75 percent of the previous time.
APFS has been in the works for several years, and available to macOS testers for data drives since the 2016 WWDC -- so this isn't technically a new product.
The results on the SATA-3 SSD in the Mac mini were more dramatic. A boot from a fully shut down state normally took about 42 seconds. Following High Sierra installation, boot times dropped to 64 percent of that in Sierra, taking only 27 seconds.

File copies and access

Copying files is a little different on APFS drives. The new file system "clones" files, as opposed to a bit-by-bit copy when on the same drive. This is, in essence, a fancy alias. When the user alters the cloned file, only the changed blocks are saved to the drive.

APFS is fully compatible with HFS-formatted disks. Copying files to or from an APFS drive is limited by the slowest link in the chain, be it the HFS drive, or the connection method. However, APFS to APFS copies across different drives removes some of the overhead associated with HFS, and can lead to some faster copies.




Across a wired or wireless network, there is essentially no statistically significant change. Using the MacBook Pro and a Mushkin Ventura Ultra USB 3.0 SSD formatted with HFS, a 30 GB folder of 1250 MP3 files of varying sizes took four minutes and 51 seconds.

When we reformatted the drive to APFS, the same copy took three minutes and 22 seconds. Copying fewer, larger files, the gains aren't as pronounced, saving only seconds per file.

Space saved

With iOS 10.3, users were sometimes seeing massive amounts of freed space as a result of the new file system, and the same appears to be the case. Prior to downloading the installer on our two test beds for High Sierra, the MacBook Pro had 222 GB used for the system, applications, and a large number of documents with nearly no duplications. The Mac mini had 64 GB full with very few documents.

Following installation, the MacBook Pro shrunk to 202 GB used -- nearly a 10 percent savings. The Mac mini had much smaller gains both in absolute size and as a percentage, with only 2 GB freed.

That suggests that APFS is more efficient at storing smaller files, which our working documents tend to be. To further test the theory, the Mac mini was restored to the backup from Sierra, with our working documents moved over -- but not the apps. Following the file transfer, but pre-High Sierra installation, the SSD on the Mac mini had 203 GB of data stored.

After High Sierra installation, the Mac mini gained 19 GB of space, a similar result to the install on the MacBook Pro.

AppleInsider expects that the savings experienced by each user depends on what kind of files they are, and the sizes of the files.

Other features

Also implemented with APFS is ability for APFS volumes to grow and shrink dynamically in a future version of High Sierra, so multiple partitions can expand and contract as needed automatically. At present, this must be done in the terminal.

Snapshots can be saved, allowing for read-only copies of a file system for easy restoration.

AppleInsider will examine more of these features at a later date.

Current limitations

If you've got an older Mac with only a hard drive, it won't be converted by default. Additionally, some iMacs with 3TB Fusion drives and BootCamp may be "unsupported," according to Apple's release notes.

Also, if you have a 2012 Mac Pro, you're out of luck for now. Apple notes that it will be included in an upcoming seed. AppleInsider will test with the 2012 Mac Pro when support is added.

If you've formatted a storage volume for APFS, it will only mount on Sierra and High Sierra systems. Older versions of macOS and all versions of Windows won't be able to read the drives.

There are some other sundry software bugs associated with APFS. Third-party utilities that hit the file system hard need to be updated with Carbon Copy Cloner already supporting the file system in its own beta. Microsoft Outlook won't load message bodies from an APFS volume -- but that's up to Microsoft to fix.

As a reminder, High Sierra, and all it encompasses,is in beta. Hammering out these bugs is why Apple runs these tests.

That all said, APFS has been in the works for several years, and available to macOS testers for data drives since the 2016 WWDC -- so this isn't technically a new product. Apple seamlessly migrated the iOS user base to it in iOS 10.3, so we're confident that this will go smooth when it ships in the fall.
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Comments

  • Reply 1 of 57
    Rayz2016Rayz2016 Posts: 3,806member
    Firing on all cylinders. 
    magman1979schlackericthehalfbeeuniscapewatto_cobrafastasleepstanthemanspheric
  • Reply 2 of 57
    elijahgelijahg Posts: 592member
    Will be interesting to see if Alsoft brings out a new version of Diskwarrior for APFS, as its so different from HFS.
    edited June 2017 horvaticneo-tech
  • Reply 3 of 57
    johnbearjohnbear Posts: 83member
    rare around here, but a very interesting article and exactly what I was looking for. 
    alphafoxrevenant
  • Reply 4 of 57
    magman1979magman1979 Posts: 1,015member
    elijahg said:
    Will be interesting to see if Alsoft bring out a new version of Diskwarrior for APFS, as its so different from HFS.
    Indeed, at work I have DiskWarrior on a few Mac's, especially servers, and find it an amazing tool for repairing volumes in the event of issues. Hope this, and other tools like it, come out with APFS-compliant versions quickly! I LOL'ed really hard at the note about MS Outlook 2016 unable to load message bodies on APFS volumes, just goes to show, once again, how shitty MS code is!
    horvaticwatto_cobraelijahg
  • Reply 5 of 57
    coolfactorcoolfactor Posts: 1,247member
    You'd think that filesystem access was fully abstracted for applications, handled entirely by the OS, so it's strange that MS Outlook 2016 is having this issue. They must've done something proprietary, which is par for the course for them.
    chabigarlomediawatto_cobrapakittwillcropointdysamoriafastasleepDuncanABaines
  • Reply 6 of 57
    teknishnteknishn Posts: 29member
    You'd think that filesystem access was fully abstracted for applications, handled entirely by the OS, so it's strange that MS Outlook 2016 is having this issue. They must've done something proprietary, which is par for the course for them.
    This one was weird. I installed the latest version of outlook from the fast track and it solved the problem though. 
  • Reply 7 of 57
    appexappex Posts: 687member
    Does APFS sport self Healing as ZFS had?
    edited June 2017 tipoo
  • Reply 8 of 57
    horvatichorvatic Posts: 94member
    Fusions drives will have to be included later as Apple just released new iMacs with Fusion drives as standard. I don't think they will let this stand as it is. At least I hope not.
    watto_cobrapakitt
  • Reply 9 of 57
    lkrupplkrupp Posts: 6,091member
    Is the conversion to APFS automatic or does it require user action? To wit, I currently have a late 2013 iMac 14,2 with a 1TB Fusion drive running Sierra on HFS+. What happens when I install High Sierra on this machine?
    mwhitewatto_cobra
  • Reply 10 of 57
    elijahgelijahg Posts: 592member
    elijahg said:
    Will be interesting to see if Alsoft bring out a new version of Diskwarrior for APFS, as its so different from HFS.
    Indeed, at work I have DiskWarrior on a few Mac's, especially servers, and find it an amazing tool for repairing volumes in the event of issues. Hope this, and other tools like it, come out with APFS-compliant versions quickly! I LOL'ed really hard at the note about MS Outlook 2016 unable to load message bodies on APFS volumes, just goes to show, once again, how shitty MS code is!
    It is absolutely brilliant, I run it fairly regularly and whilst Apple's fsck_hfs finds no problems, DW finds and repairs plenty. Even fairly critical things like number of free blocks, or file count fsck seems to miss. 

    I did too, block level access to the disk requires admin privileges though, so unless MS has the setuid bit set on something (mighty dangerous, so likely) they can only use normal file system access APIs. So no idea what they've done. Typical though.  
    watto_cobra
  • Reply 11 of 57
    wonkothesanewonkothesane Posts: 1,171member
    I wonder if older Macs where Sierra runs through a patch will support APFS. Here, one machine in question is a 2009 MBP. 
    watto_cobra
  • Reply 12 of 57
    schlackschlack Posts: 672member
    Rayz2016 said:
    Firing on all cylinders. 
    Firing on a single cylinder while representing the differential positions of the other cylinders to save space.
    chabighmurchisontallest skilwatto_cobrabestkeptsecretspheric
  • Reply 13 of 57
    libertyforalllibertyforall Posts: 1,179member
    So will Time Capsule support bring APFS formatted?  
    pakitt
  • Reply 14 of 57
    melgrossmelgross Posts: 30,523member
    The only thing that bothers me is the file copy. When I copy a file, I'm doing it for a reason. I want an exact copy. If I alter one, I don't necessarily want the other altered. If one gets corrupted, rare, but it does happen, I want the other pristine one to replace it. I'm not sure how this will work.

    its a reason why I'm not fond of de-duping. My copies are intentional.
    robbyxspheric
  • Reply 15 of 57
    Mike WuertheleMike Wuerthele Posts: 2,887administrator
    lkrupp said:
    Is the conversion to APFS automatic or does it require user action? To wit, I currently have a late 2013 iMac 14,2 with a 1TB Fusion drive running Sierra on HFS+. What happens when I install High Sierra on this machine?
    The existing installation has a check-box on the first page that's selected by default for the migration on SSD-based machines. That's obviously subject to change.
  • Reply 16 of 57
    Mike WuertheleMike Wuerthele Posts: 2,887administrator

    So will Time Capsule support bring APFS formatted?  
    It doesn't right now. However, the limiting factor in that transfer is the network, and not the file system.
  • Reply 17 of 57
    Mike WuertheleMike Wuerthele Posts: 2,887administrator

    I wonder if older Macs where Sierra runs through a patch will support APFS. Here, one machine in question is a 2009 MBP. 
    I have some concerns about this. I wouldn't expect it.
  • Reply 18 of 57
    For Outlook, I imagine it has something to do with going from case-insensitive HFS+ to case-sensitive APFS.
    tenthousandthingswillcropoint
  • Reply 19 of 57
    macxpressmacxpress Posts: 4,447member
    So how does something like imaging work with APFS? I've heard imaging will no longer be supported after upgrading to macOS High Sierra. They want you to go MDM and I guess maybe restoring instead of reimaging like you currently can. 
  • Reply 20 of 57
    lkrupp said:
    Is the conversion to APFS automatic or does it require user action? To wit, I currently have a late 2013 iMac 14,2 with a 1TB Fusion drive running Sierra on HFS+. What happens when I install High Sierra on this machine?
    It will do an in-place conversion to APFS automatically. The same as happened on iOS 10.3.
    watto_cobra
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