Apple Debuts New SSD-Optimized APFS File System

Posted on June 14, 2016 By Pedro Hernandez

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Apple seems ready to move on from its decades-old Hierarchical File System (HFS)-based storage roots.

During the company's Worldwide Developer Conference (WWDC) in San Francisco today, the company is holding a session to educate attendees on the new Apple File System (APFS), which will feature in a wide range of devices from the Apple Watch to high-end Mac Pros. First, APFS is optimized for solid-state drives (SSDs) and other forms of flash storage, claims Apple.

"HFS+ and its predecessor HFS are more than 30 years old," wrote the company in online documentation regarding the upcoming file system. "These file systems were developed in an era of floppy disks and spinning hard drives, where file sizes were calculated in kilobytes or megabytes. Today, solid-state drives store millions of files, accounting for gigabytes or terabytes of data."

Like its predecessor, APFS supports TRIM commands to help extend the life of SSDs. In the case of APFS, TRIM operations are handled asynchronously, an approach that ensures that helps minimize wear.

Secondly, APFS builds upon the full disk encryption feature in OS X and file encryption capabilities in iOS to protect data on Apple devices.

"APFS supports encryption natively. You can choose one of the following encryption models for each volume in a container: no encryption, single-key encryption, or multi-key encryption with per-file keys for file data and a separate key for sensitive metadata," explained Apple.

Depending on the type of hardware used, APFS uses AES-XTS or AES-CBC encryption. Further, it can help safeguard user data even if a device's physical security is bypassed, Apple claims.

The base storage unit for APFS is called a container, which can export one or multiple volumes, each with its own namespace, explained the company. APFS improves upon the 31-bit file IDs in HFS+ by supporting 64-bit inode numbers. Inode is a data structure that contains information about a file in Unix file systems.

APFS features timestamp granularity down to the nanosecond, a big jump from HFS+ timestamps that can record file activity in terms of full seconds. APFS also includes sparse files support and a copy-on-write metadata crash protection system. An extensible block allocator that initializes data structures as necessarily when it encounters large storage devices, a tactic that can improve performance, according to Apple.

APFS will be the file system for OS X (soon MacOS), iOS, tvOS and watchOS devices after it ships sometime in 2017. Early adopters can test the new file system as part of a developer preview in OS X 10.12.

Pedro Hernandez is a contributing editor at InfoStor. Follow him on Twitter @ecoINSITE.


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