With the launch of Mac OS High Sierra, Apple's new file system apfs has become standard in all its operating systems. Apfs (Apple File System) is the company's first new file system since hfs + launched in 1998. It was in turn only an update of hfs released in 1985 with Apple's first Macintosh Hard Disk.
Apfs is a modern file system that takes ideas from many places to be as robust and future-proof as possible. It is developed with flash memory as the main storage medium, but can be used on other media as well.
The switch to a new file system is a major conversion and there are many who have questions about different things. In this article we collect the answers to the most common questions and suggest some solutions to problems that may occur.
Why has Apple developed apfs? What are the benefits?
Hfs + has become very old and is a patchwork of different techniques to keep it alive. Apfs is adapted to modern requirements and applications. Because SSDs are worn by typing operations, apfs are customized to minimize these, including by reusing data as much as possible. For example, you notice if you duplicate a large file – it happens almost immediately, no matter how big it is. Backblaze has written a great review of apfs that goes through the many benefits in detail.
High Sierra automatically updates to apfs, can I prevent it?
Yes! It may not work because there is no trace of any options in the installer, but via Terminal you can still launch an update that skips apfs conversion.
What problems can occur with apfs?
It has been reported that some games do not work in High Sierra with apfs, including Civilization V. Some of these have been updated by now, while others work if you place them on another disc or in a disc with hfs +, so it should not be enough to avoid the update.
Is it possible to return to hfs + if I have updated to apfs?
No, not without reformatting and thus deleting all data on disk.
Can I still use clone programs to back up my boot?
Yes, but with some things to think on. Both Superduper and Carbon Copy Cloner have been updated with support for apfs. Perhaps the safest way to update the clone is to start the Mac from your latest clone with Mac OS High Sierra, update it to apfs and let it update the file system to apfs, and then start cloning from Mac's built-in disk to the now updated clone.
Will Apple Stop Supporting Hfs +?
Not in the foreseeable future, but probably fewer and fewer features will work with hfs +. Time Machine, for example, learns pretty soon require apfs. The actual Mac OS will probably switch to being able to boot from apfs only within a few years.
Should I update my external drives to apfs?
If you do not need encrypted disks you can update and if It's an external ssd we can even recommend it because apfs are more efficient and better at minimizing the number of writing operations, which can increase the life span of it. Keep in mind that systems older than Mac OS Sierra can not read or write apfs disks.
Apfs has built-in encryption support, does it mean I can turn off Filevault?
No. File OSult in Mac OS High Sierra uses apf's built-in encryption feature, but if you turn it off, no encryption is used at all. Just because there is support for something does not mean that it is automatically enabled.
Affects apfs Time Machine by any means?
Yes and no. If you have a Time Machine backup on an external disk or Time Capsule and it's hfs + format, it will continue to be and work as usual. But Mac OS High Sierra with apfs uses a new feature called snapshots to create temporary backups while outside the home. This makes your free hard disk space appear to shrink in an unnatural way, but as soon as you get home and Time Machine, its free space is released.
I've updated to Mac OS High Sierra and my free storage space looks out to commute wildlife, and when I empty the trash, it does not seem to help at all. What is the matter?
See the above answers. It's about Time Machine can create snapshots to secure precise backups. If Time Machine is enabled but the computer does not have access to the backup disk, the system will save everything until it has, which means you can not free up more space by deleting files until you have connected it again.