ZFS: The Last Word in File Systems Part 1
Deirdré Straughan4 HN recommenders · recommended in 4 months, 2016–2026
talk · intermediate · evergreen · 2016–2026 on HN
Jeff Bonwick and Bill Moore, the creators of ZFS, present 'ZFS: The Last Word in File Systems' at the 2008 SNIA Software Developers' Conference. They explain the design, including copy-on-write, checksumming and avoiding the write hole.
HN recommends it as the definitive explanation of ZFS design straight from its inventors, with war stories about data integrity.
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6 comments from Hacker News
ZFS was an inspiration for TigerBeetle. I love this talk by Jeff Bonwick and Bill Moore: “ZFS: The Last Word in File Systems” ▶ this video
> Is ZFS any good? The presentation "ZFS: The Last Word in File Systems" from its debut in 2008 is a good introduction. Part 1 (of 3) probably best explains how different it is from just about anything else out there (even now, in 2019): * ▶ this video Part 2 show some extra niceties / features, and Part 3 is a demo and Q&A. Watching Part 1 at least is worth it for anyone curious; 2 and 3 are optional.
I would recommend anybody interested in filesystems to watch Jeff Bonwick (ZFS inventor) explain the design of ZFS: ▶ this video . They have a few very nice war stories explaining why they found it useful to have the user data checksummed as well.
ZFS: The last word in File Systems: Part 1: ▶ this video Part 2: link ZFS In the trenches: link Some good stuff here: link
> initial issues You mean like the current advice not to use anything except mirroring and striping (RAID-0/1/10)? > Parity may be inconsistent after a crash (the "write hole"). The problem born when after "an unclean shutdown" a disk failure happens. But these are two distinct failures. These together break the BTRFS raid5 redundancy. If you run a scrub process after "an unclean shutdown" (with no disk failure in between) those data which match their checksum can still be read out while the mismatched data are lost forever. * link I've been using ZFS since it came out on Solaris 10 over a decade ago and it was specifically designed not to have a write hole due to its COW/ACID nature. See this 2008 SNIA presentation from Bonwick and Moore, the creators of ZFS talking about not having a write hole: * ACID/COW: ▶ this video * Integrity: ▶ this video
Well, ZFS isn't exactly monolithic if you look under the hood: it has the ZPL (files, directories), DMU (objects, transactions on those objects), SPA (actual disk I/O). A potato-quality video from 2008 with Moore and Bonwick, the creators (timestamped to relevant section): * ▶ this video