The blog post explores the history of Apple's rumored adoption of ZFS, the advanced file system. While Apple engineers internally prototyped and tested ZFS integration, ultimately licensing and legal complexities, combined with performance concerns specific to Apple's hardware (particularly flash storage) and the desire for full control over the file system's development, prevented its official adoption. Though ZFS offered appealing features, Apple chose to focus on its own in-house solutions, culminating in APFS. The post debunks claims of a fully functioning "ready to ship" ZFS implementation within OS X 10.5, clarifying it was experimental and never intended for release.
Adam Leventhal's blog post, "ZFS: Apple's New Filesystem that wasn't (2016)," delves into the historical flirtation between Apple and the ZFS filesystem, ultimately explaining why the promising union never materialized into a shipped product. Leventhal begins by setting the stage in the mid-2000s, a period when Apple was actively seeking a successor to their aging HFS+ filesystem. ZFS, with its advanced features like copy-on-write, snapshots, checksumming, and dynamic striping, appeared to be a compelling candidate. This potential was further amplified by Sun Microsystems, the creators of ZFS, open-sourcing the filesystem under the Common Development and Distribution License (CDDL). Apple even hired Don Brady, a key ZFS engineer, fueling speculation of imminent ZFS integration into macOS.
The blog post then highlights a pivotal moment: the WWDC 2006 "leopard sneak peek," where Apple showcased ZFS as a potential cornerstone of their upcoming operating system, Mac OS X Leopard. Screenshots displayed ZFS volumes seamlessly integrated within Disk Utility, bolstering the perception that ZFS adoption was all but certain. However, this initial enthusiasm eventually waned.
Leventhal then carefully dissects the reasons behind Apple's eventual abandonment of ZFS. He points to the licensing incompatibility between the CDDL and Apple's proprietary software ecosystem as a significant hurdle. Integrating a CDDL-licensed component into macOS could potentially create legal complexities and restrict Apple's ability to maintain tight control over their operating system's codebase. Furthermore, the blog post mentions Sun Microsystems' acquisition by Oracle in 2010, introducing further uncertainty into the future of ZFS and potentially complicating any pre-existing agreements between Apple and Sun.
The author also explores technical challenges that might have contributed to Apple's decision. While ZFS boasted impressive features, its performance characteristics may not have been ideally suited for Apple's hardware, particularly on systems with limited RAM. The memory intensity of ZFS, although beneficial for data integrity and performance in certain scenarios, could have posed a problem on lower-end Mac configurations.
Finally, Leventhal concludes that while ZFS integration into macOS seemed promising at one point, a combination of licensing conflicts, the Oracle acquisition of Sun, and potential performance considerations ultimately led Apple to pursue alternative filesystem solutions. He underscores the missed opportunity, acknowledging the potential benefits ZFS could have brought to macOS users, but ultimately recognizing the complex factors that influenced Apple's final decision. The post serves as a retrospective analysis of a significant "what-if" moment in Apple's history, illuminating the intricate interplay of technical capabilities, legal constraints, and business strategy that shape technological advancements.
Summary of Comments ( 63 )
https://news.ycombinator.com/item?id=43810566
HN commenters discuss Apple's exploration and ultimate rejection of ZFS. Some highlight the licensing incompatibility as the primary roadblock, with ZFS's CDDL clashing with Apple's restrictive approach. Others speculate about Apple's internal politics and the potential "not invented here" syndrome influencing the decision. A few express disappointment, believing ZFS would have significantly benefited macOS, while some counter that APFS, Apple's eventual solution, adequately addresses their needs. The potential performance implications of ZFS on Apple hardware are also debated, with some arguing that Apple's hardware is uniquely suited to ZFS's strengths. Finally, the technical challenges of integrating ZFS, especially regarding snapshots and Time Machine, are mentioned as potential reasons for Apple's decision.
The Hacker News post discussing the article "ZFS: Apple's New Filesystem that wasn't" contains a robust discussion with several compelling comments.
Several commenters discuss the licensing incompatibility between ZFS's CDDL and Apple's macOS/iOS ecosystem. One commenter succinctly explains that while Apple could have theoretically re-licensed their OS, the effort and potential instability would have outweighed the benefits. They suggest the legal complications were likely insurmountable. Another clarifies the nuanced differences between "GPL infectiousness" (which ZFS/CDDL doesn't have) and the practical impossibility of integrating CDDL code into a proprietary derivative work like macOS. This incompatibility issue is the central theme of many comments.
Another thread dives into the technical aspects of ZFS and why it might have been appealing to Apple. One commenter praises ZFS's snapshotting and checksumming capabilities, highlighting the potential for a more robust and reliable file system for macOS. However, another points out the performance overhead ZFS could introduce, particularly with Apple's focus on flash storage at the time. The discussion explores the trade-offs between features like data integrity and raw speed, suggesting Apple likely prioritized the latter for their target hardware and use cases.
Several commenters reminisce about the anticipation surrounding the rumored integration of ZFS into macOS and the subsequent disappointment. One shares personal anecdotes about testing early ZFS implementations on OS X, hinting at the promise that ultimately went unfulfilled.
The performance characteristics of ZFS are debated, with some arguing its RAM requirements would have been prohibitive for mainstream adoption on Apple hardware at the time. Counterarguments suggest that ZFS's design could have benefited from the increasing RAM capacities in later Apple machines.
Finally, some comments touch upon the political and business dynamics between Apple and Sun Microsystems (later Oracle), speculating about the potential role these relationships played in the decision. While mostly conjecture, these comments add another layer to the discussion surrounding the failed integration.
In summary, the comments section provides a multifaceted perspective on the ZFS and Apple situation, covering the legal, technical, and historical aspects of the unfulfilled integration. The discussion highlights the complexities of software licensing, the trade-offs in filesystem design, and the realities of business decisions within the tech industry.