Meet APFS: Apple’s new file system
A new underlying file technology makes a subtle debut in macOS Sierra
The file sys tem is a vitally important part of any operating system – as it sounds, it’s the layer responsible for handling the raw files, and the operations around them. This leads to a dilemma for companies like Apple: you don’t want to to change it often, because getting it wrong can potentially break… everything, really. But you also don’t want to be stuck with an old one that makes it difficult to implement important features. Apple has been using its current file system, HFS+, for nearly 20 years – but its time is running out, because macOS Sierra includes a preview of a system named APFS.
One of APFS’s primary purposes appears to be to make features that Apple is already doing easier on the system. For example, it includes support at the file system level for “snapshots” and “clones.” The former can identify differences between files and folders, meaning that Time Machine could become faster and use less resources to run. The latter can seamlessly copy a full version of a file, enabling the Versioning feature to run more smoothly. Right now, OS X handles these tasks at a higher level, which is inherently less efficient.
One of the biggest additions is native support for encryption at the file level, which can replace FileVault, once again offering a much faster and less processorintensive solution. It’s also more granular: instead of encrypting the whole disk, you can secure just one folder, or a single user’s files. It will make having your files encrypted just a normal part of owning the machine, like it is on iOS.
Other useful features include “fast directory sizing,” which means you won’t have to wait for lengthy checks to see how much space a giant file or folder uses, and “sparse files,” which make more efficient use of disk space. There’s also a feature that protects files from damage if there’s a crash or a power outage while they’re being written to.
The reason Apple didn’t make a bigger deal of it is that it’s not ready yet. Its inclusion in Sierra is very limited (it can’t be applied to your boot drive or a Time Machine drive) – just for testing purposes. Apple needs to get it right, because a bug in a file system can lose gigabytes of data at a time. It’s expected to be in full use in 2017. Apple is also planning an open source release of its code next year, making it available to other companies to implement.