archiso-zfs VS httm

DKMS is the best option if you really want to keep up with Arch updates and if you're experienced with Linux (for instance you know how to fix your system from the archiso if needed -- for ZFS you'll need to manually load the zfs module from the archiso; this script is very helpful).

Make an EFI boot partition of maybe 200MB using your favorite distro iso and make a zpool on a second partition of the remaining space followed by a single dataset on that zpool named root at the minimum with normalization=formD, compression=lz4 or zstd and optional encryption flags and install your rootfs to that. I've found this process is easiest using the Archlinux ISO and this github project to get zfs in the archiso environment.

The script available there: https://github.com/eoli3n/archiso-zfs makes it extremely easy to add ZFS support to any Arch ISO after it has booted. You can copy any standard ISO to a USB drive, boot off it, then run `curl -s https://raw.githubusercontent.com/eoli3n/archiso-zfs/master/... | bash` and you'll have ZFS support in a few seconds, without having anything to worry about.

With Arch there is an easy way to get the iso to read ZFS with a simple script, it is a bit of a no no unless you verify the script before using it. https://github.com/eoli3n/archiso-zfs

My own experience is with ZFS, first on Arch Linux (using the excellent https://github.com/eoli3n/archiso-zfs). I learned a lot doing that and modifying the scripts to my liking.

You can load zfs modules in the archiso with: https://github.com/eoli3n/archiso-zfs

Because zfs isn't part of the mainline kernel -- you need to add the appropriate packages during the install process -- meaning you need to either boot from a standard Arch ISO install disk and then download the packages as explained here: https://github.com/eoli3n/archiso-zfs or you need to make a custom arch ISO where you add the zfs packages. https://wiki.archlinux.org/title/ZFS#Create_an_Archiso_image_with_ZFS_support. The only issue with creating the custom ArchISO -- you need an actual basic arch installation somewhere to create the disk -- so basically you need a standard Arch installation to create a custom install disk whereby you can install an Arch zfs installation. Here are other good tutorials for this: https://ramsdenj.com/2016/06/23/arch-linux-on-zfs-part-1-embed-zfs-in-archiso.html

Both ZFS updates and pacman breaking are rare enough that I forgot that would happen. Though using this rescue system would work, there's also a group that maintains a script to grab the correct ZFS module for a running archiso, might come in handy for you.

https://github.com/eoli3n/archiso-zfs

You're having a problem due to archiso not updating every time the kernel updates, though you could fix this issue there's also just an easier way. The archzfs repo group has made a tool to grab the correct zfs module for the running kernel, see https://github.com/eoli3n/archiso-zfs

My projects and many projects include a THIRD-PARTY-LICENSES.html file when I distribute binaries. See: https://github.com/kimono-koans/httm/blob/master/third_party/LICENSES_THIRD_PARTY.html

The only real advantage I can think of with nested ZFS is that the files in the KVM would obviously be individual inodes in the nested ZFS filesystem and datasets, in addition to the one inode per virtual volume on the hypervisor (or zvol). This would allow for granular file management on the kvm and the use of tools like https://github.com/kimono-koans/httm which is like a command line time machine for ZFS.

> It's worth noting that copy_file_range is used by a lot of things.

Yes, but the trigger feature, block cloning, only landed in the latest 2.2 release. If you immediately hopped on 2.2, and used a system with lots copy_file_range and FICLONE use, yes, you may have a problem (like, as you note, on Gentoo, where this problem surfaced).

Most people were just hopping on the bandwagon. My distro ships 2.1.5, so I have a 6 month wait until this feature lands, so I was just building copy_file_range support into my ZFS apps, right before news of this bug hit.[0]

> There are other things required to trigger the bug that are a lot less common though.

Exactly. My guess is the incidence of this will exceedingly rare for the common user/small NAS user/etc. I've run a corruption detector[0], and what I've found mostly indicates false positives. Some are build artifact fingerprints, which I don't care about, and which were deleted with the next build. The ones with an extant file on another system, I confirmed were a diff match with the origin using `rsync -rincv` and whats on snapshots with `httm --map-aliases`. So far no positive matches.

[0]: https://github.com/kimono-koans/httm

cargo install --git https://github.com/kimono-koans/httm --branch clones strace -f -o stderr.txt -e ioctl -- httm -r -R ~/.zshenv

httm prints the size, date and corresponding locations of available unique versions (deduplicated by modify time and size) of files residing on snapshots, but can also be used interactively to select and restore files, even snapshot mounts by file! httm might change the way you use snapshots (because ZFS/BTRFS/NILFS2 aren't designed for finding for unique file versions) or the Time Machine concept (because httm is very fast!).

All btrfs snapshot tools can have different layouts. It's mostly a nightmare for any one tool to support. Although its not the tool you're looking for, FYI AFAIK httm supports all/most btrfs layouts, but it took more work than necessary to get there.

ZFS only option which requires super user privileges.

[0]: https://github.com/kimono-koans/httm/blob/master/httm.1

httm - Interactive, file-level Time Machine-like tool for ZFS/btrfs/nilfs2