OpenZFS for Mac

The current version is 2.3.0. Lately, the old site https://openzfsonosx.org/ is unreachable. Now, all that is available is at https://github.com/openzfsonosx/openzfs-fork. You won't find any version prior to 2.2.2 there, and it's a real shame as v2.1.0 was the last to run perfectly on old MacOS (from 10.9 until 10.15 or 11). v2.3.0 is working ok, though, maybe a little slower than 2.1.0 but definitely better than 2.2.2 and 2.2.3. The dev mentioned his intention to move everything to github, but the old forum was a source of inspiration in case of issues... For example, you have to do some modification to have ZFS running well on 10.9. In addition to my big backups, I now use a ZFS pool for my VMs, some huge applications and the biggest folders in Application Support (through symbolic links). All those benefit from ZSTD compression, it's specifically noticeable with the VMs, as there's a lot of data to write, so it's faster too than on APFS.

v2.2.2 was released one year ago, it's working ok on my system (using it mainly in 10.14, but it looks ok in 10.11 and quite ok in 10.9 — I guess it's ok on recent MacOSes, as it's being developed for them in the first place 😉). There's still a good point in using ZFS nowadays, it's for Virtual Machines: they are one of few cases where you take advantage of the integrated compression algorithms. V2 introduced ZSTD with various flavours and you easily achieve a compressratio of 1.66x (1 being not compressed). Sp****bundles are another case where you can achieve a compressratio of 2.64x! (my own tests). So if you have a partition populated with VMs and sp****bundles, you can save a lot of space. 👍

v2.1.0 has been out since last august and should work ok in recent MacOSes (I have only tested 10.11 and 10.14 last year, but stayed with v1.9.4 as compatibility with 10.9 has never been fixed — and as I wrote in my precedent review, there's little interest for using it over APFS if you don't need compatibility with some other OS). I keep using it for my monthly backup though, mainly out of habits, but I clearly could devise another strategy without ZFS...

Current version is 2.0.1. Time for another small review. After 6+ years using OpenZFS on OS X, I've just finished restructuring my drives, only keeping ZFS for long time backups on a single zpool — i.e. the way it's meant to be, not slices scattered on one or more drives, even if it's possible and I've used it that way until now. When I read my old reviews here, it's clear that it has become a lot slower and is not suited for daily personal computer use (putting your /Users on a zpool and things like that). Sure enough, ZFS is still a great and secure filesystem and a reliable choice if you value your data more than speed. There are issues, though, even if they are perhaps not directly attributable to OpenZFS, but I often had crashes where zfs kexts are in the backtrace, in recent versions at least. While restructuring my drives, I also had lightning KP where the computer reboots abruptly when copying huge folders or sparsebundles using the Finder, and no trace of anything in the Console! :-o Using apps like Carbon Copy Cloner or Terminal (with the ditto command) works perfectly, so it's very likely that Finder is the culprit here, as it has proved many times not being the most reliable piece of software in history... :-D The point with OpenZFS on OS X is that there's only one very busy dev working on it, so development is understandably going at a crawl and some issues are not fixed, especially if they happen on old versions of MacOS. To end on a positive note, I still recommend it for reliable backups but better forget any kind of acrobatics. ;-)

Current version is 1.8.2. Time for a small review. After nearly 4 years using OpenZFS, my early enthusiasm has waned... All in all, knowing how it has evolved, I kind of regret a bit my installing it. Not that ZFS has become a bad filesystem, but the development of the Mac port is really slow in fixing the issues, the devs don't have much time to dedicate to that project and you must make enough trials before updating to a new version. I had to skip a few versions last year before they fixed an important issue I had (took one and a half year before I can update with peace of mind...) — I don't even dare posting issues on their forum any more, as one dev has been pretty rude to me a few years ago, with no reason (see one of my posts below) and I generally get no answer. Luckily, the issues have always been non-destructive, and once you've got a version that works it's ok. I want to believe that if you dedicate a full disk to one big ZFS pool, you'll meet zero issue. But having a few pools scattered amongst HFS+ partitions like me is probably showing issues that wouldn't arise otherwise — and this is an issue for me, as ZFS is still not bootable, AFAIK. Well, I'm probably not the target for ZFS, after all, even though I can't update to MacOS 10.13 and enjoy APFS... So, if you absolutely need ZFS or are of the geek kind (like me ;-) ), go for it, but now that APFS is here, there's no need for ZFS for the average user.