Apple announces new APFS file system for macOS, iOS, and more

June 14, 2016 // 9:52 a.m.

Tags: #apfs #apple #apple-file-system #encryption #file-system #hfs #macos #os-x #sierra #yosemite

Apple has announced that it is to replace its ageing HFS+ file system in the next version of its operating systems, announcing a replacement dubbed Apple File System or APFS.

Announced at the same time as a rebrand that will see OS X return to its roots as macOS - with hip initial lower-case m, of course - with the launch of macOS Sierra, APFS is Apple's first major new file system for thirty years - HFS+ being little more than a layer of spit and polish over the ancient HFS. 'HFS+ and its predecessor HFS are more than 30 years old. These file systems were developed in an era of floppy disks and spinning hard drives, where file sizes were calculated in kilobytes or megabytes,' Apple admitted in its developer documentation for the new APFS. 'Today, solid-state drives store millions of files, accounting for gigabytes or terabytes of data. There is now also a greater importance placed on keeping sensitive information secure and safe from prying eyes.'

APFS, Apple claims, includes a range of improvements over HFS and HFS+: a shift to 64-bit inode numbers from 32-bit file identifiers means a boost in the total number of files supported on each file system; timestamps can now have granularity of just one nanosecond instead of one second; lazy block allocation improves performance on larger volumes; copy-on-write (COW), a feature of rival file systems including XFS and Btrfs, ensures crash protection; and extended attributes are supported.

The biggest change, however, comes from the integration of encryption directly into the file system itself - distinct from the company's previous approach of offering an encryption layer which sits above the file system. Using APFS, Apple has explained, volumes can be initialised with no encryption, single-key encryption, or multi-key encryption which uses separate keys for file data and metadata.

Interestingly, Apple has no plans to backport the format to earlier operating systems: while APFS will become the default file system for macOS 10.12 Sierra and the next releases of iOS, tvOS, and watchOS, it will not be compatible with OS X 10.11 El Capitan or earlier.
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