ZFS developer Adam H. Leventhal writes an in-depth comparison between ZFS–a prominent filesystem in BSD systems, and APFS–a new filesystem developed for Apple’s macOS and replacing its aging HFS+. The author discusses its snapshot and backup, management, performance, efficiency, and data integrity features.
APFS, the Apple File System, was itself started in 2014 with Giampaolo as its lead engineer. It’s a stand-alone, from-scratch implementation (an earlier version of this post noted a dependency on Core Storage, but Giampaolo set me straight in this comment). I asked him about looking for inspiration in other modern file systems such as BSD’s HAMMER, Linux’s btrfs, or OpenZFS (Solaris, illumos, FreeBSD, Mac OS X, Ubuntu Linux, etc.), all of which have features similar to what APFS intends to deliver. (And note that Apple built a fairly complete port of ZFS, though Giampaolo was not apparently part of the group advocating for it.) Giampaolo explained that he was aware of them as a self-described file system guy (he built the file system in BeOS, unfairly relegated to obscurity when Apple opted to purchase NeXTSTEP instead), but didn’t delve too deeply for fear, he said, of tainting himself.
Discussion thread on /r/programming: https://www.reddit.com/r/programming/comments/4pziho/a_zfs_developers_analysis_of_apples_new_apfs_file/t1_d4pw7vc