Key Features and Limitations of HFS+

Definition: HFS+ is a proprietary journaling file system developed by Apple Inc., serving as the successor to the original HFS (Hierarchical File System). It was the default file system for macOS from 1998 (with Mac OS 8.1) until 2017, when it was replaced by APFS (Apple File System). HFS+ is optimized for Apple’s hardware and software ecosystem, supporting features tailored to macOS and classic Mac OS workflows.

Core Features

Journaling MechanismIntroduced in Mac OS X 10.3 (Panther), HFS+ journaling tracks changes to file system metadata (e.g., file creation, deletion, directory modifications) in a dedicated log file. In the event of a system crash or power failure, the journal enables fast recovery of the file system to a consistent state, reducing the risk of corruption and eliminating the need for time-consuming full disk checks (fsck).Note: HFS+ only journals metadata (not file data) by default, striking a balance between reliability and performance.
Expanded Storage CapacityHFS overcame the limitations of its predecessor HFS, which was constrained by 16-bit addressing:
- Maximum file size: Up to 8 exabytes (EB) (theoretical limit; practical limits depend on storage hardware and macOS versions).
- Maximum volume size: Up to 8 EB (theoretical), a massive leap from HFS’s 2 GB volume limit.This scalability supported large media files, disk images, and enterprise storage needs for Mac systems.
Unicode and Metadata Support
- Native support for Unicode filenames, allowing users to name files with characters from virtually any language (e.g., Chinese, Japanese, Cyrillic) without encoding issues—an improvement over HFS, which relied on Mac Roman encoding.
- Stores rich file metadata, including resource forks (a classic Mac feature for separating application code from data) and Finder information (e.g., file icons, window positions, labels). This metadata is critical for maintaining compatibility with legacy Mac applications.
Case-Insensitive, Case-Preserving BehaviorBy default, HFS+ is case-insensitive (e.g., File.txt and file.txt are treated as the same file) but case-preserving (it retains the original case of filenames when displayed). This behavior aligns with user habits in the macOS ecosystem, though it can be configured to be case-sensitive for specific use cases (e.g., cross-platform development).
Compatibility with Classic Mac FeaturesHFS+ retains support for aliases (flexible file shortcuts that work even if the target file is moved) and file locking, features that were central to classic Mac OS workflows and remained relevant in early macOS versions.

Limitations

Lack of Modern FeaturesCompared to APFS and other contemporary file systems (e.g., EXT4, ZFS), HFS+ lacks advanced capabilities like native encryption, snapshots, cloning, and space sharing. These limitations led Apple to replace it with APFS, which is optimized for SSDs and modern storage needs.
Performance on SSDsHFS+ was designed for mechanical hard disk drives (HDDs) and does not leverage SSD-specific optimizations (e.g., TRIM support was added later as a patch). It suffers from slower write speeds and higher fragmentation on SSDs compared to APFS.
Cross-Platform Compatibility
- Windows systems require third-party drivers (e.g., Paragon NTFS for Mac, HFSExplorer) to read/write HFS+ volumes.
- Linux systems have limited native support (read-only by default; write support requires additional packages and configuration).
- APFS has since become Apple’s cross-device standard, further reducing HFS+ relevance in cross-platform environments.

Comparison with APFS (Apple’s Current Default)

Feature	HFS+	APFS
Default macOS Support	1998–2017	2017–present
Journaling	Metadata-only (default)	Metadata + optional data journaling
File Encryption	No (requires third-party tools)	Native (FileVault-compatible)
Snapshots & Clones	No	Native, space-efficient
SSD Optimization	Minimal	Built-in (TRIM, copy-on-write, zero fragmentation)
Maximum Volume Size	8 EB (theoretical)	8 EB (theoretical, same as HFS+)