On Mon, 25 Nov 2024 at 09:52, David Mason via talk <talk@gtalug.org> wrote:
btrfs looks really interesting. And it's good to have an alternative to zfs, but for me, it's not yet ready for prime time.
If you have a serious amount of data that you care about, mirroring and raid1 are jokes. (See https://jro.io/r2c2/ for comparisons of what various raid levels do for you.) With disks the size they are these days, you have a fair chance of another disk failing while you're re-building the checksums from a failed disk, and if you get read errors during the process, you'll never know. So raidZ2 (what btrfs calls raid5) is a minimum. (Note that this is a particular problem if you bought a bunch of the same disks (because they were a great deal) manufactured near the same time. We have noticed contemporaneous failures!)
btrfs raid5/6 have some serious issues - a search following one of the links in the wikipedia article to: https://lore.kernel.org/linux-btrfs/20200627030614.GW10769@hungrycats.org/ and putting "raid5" in the search turns up numerous issues from the last couple of months; the SUSE support page describes a lot of (to me) very scary errors.
So I'll stick with ZFS, particularly as the license issue seems to be "ancient" history.
I used an off-hand expression in my discussion of ZFS, and as usual I'm paying for that. It's fairly easy to use ZFS with Linux, so my characterization of "nightmarish license problems" was ... hyperbole. But on Debian at least, which honours both the GPL and the ZFS licensing, the system must download and build the ZFS kernel drivers every time there's a kernel update. This is because OpenZFS inherited the deliberately obstructive licensing from Solaris that - although otherwise "open source" - does not allow shipping binaries to a GPL system. As I understand it, this was intentional on the part of Solaris and relicensing with the hundreds of developers who submitted code under that license is essentially impossible. If Ubuntu is shipping ZFS binaries with the Linux kernel, they're breaking license rules. They may not care, but distros like Debian who have less lawyers on tap and a stronger moral compass may not feel comfortable doing this. What this means in practice is that a weekly `apt update && apt full-upgrade` that includes a kernel averages 1-2 minutes on most Debian machines that don't have ZFS installed, and 10 minutes on machines that do have it installed. This is a significant PITA (although not, I admit, "nightmarish"). It means an action you thought would be short - is not. It's enough that I've learned to avoid ZFS on my desktops and only use it on multi-drive systems - and even there I find it a bit annoying. Thanks everyone for the comments on btrfs: I managed to do a bit more research in the intervening time, and it amounted to everything everyone said on this list. Btrfs is good but there are a couple significant blocks: lack of native encryption, lack of good RAID 5/6, lack of complete recovery tools (still being developed). Developing file systems must be particularly hard: beta software at worst wastes your time, beta FSes at worst nuke your data. Slightly different risk levels. -- Giles https://www.gilesorr.com/ gilesorr@gmail.com