So I wouldn't use ZFS again. Next time I would adopt B-tree FS (BTRFS) which isn't trapped by restrictive licensing or mdadm.

This is my log from installing ZFS on the root of Devuan, with a mirrored (two hdd) setup. tl;dr everything works.

This is the main guide
https://github.com/zfsonlinux/zfs/wiki/ … oot-on-ZFS

I see this guide:
https://www.klaus-hartnegg.de/gpo/2017- … evuan.html

but I don't think it's necessary to install from compilation in ASCII.
He mentions (in a side box, which is easy to miss)
"Installing zfs-dkms from contrib
in Devuan 2 works
like described here,
but it is old version 6.5.9."

I don't mind the old version, as it's likely to be stable. That's why it's in the repos.

I'm using an x86-64 devuan ascii minimal live cd. You should be using x86-64.

Steps:

First add contrib archive to existing apt/sources

e.g.
deb http://pkgmaster.devuan.org/merged ascii main
to
deb http://pkgmaster.devuan.org/merged ascii main contrib

I'm using apt-get not apt. Both should work.
apt-get install debootstrap gdisk dpkg-dev linux-headers-$(uname -r)

follow the zfsonlinux guide
I'm using mirrored root.

this command:
sgdisk -a1 -n2:34:2047  -t2:EF02 /dev/disk/by-id/scsi-SATA_disk1

-a means set sector alignment
-n is make new partition. here it is partition 2 with start at sector 34
end at sector 2047
-t is partition type

Note that this command uses the /dev/disk/by-id command.

sgdisk is the same functionally as gdisk and the hex codes for -t are:

I'm going to be mirroring root so I'll use this command on both drives.

sgdisk -a1 -n2:34:2047  -t2:EF02 ata-WDC_WD10JPVX-5555555_WXA1AA755555
sgdisk -a1 -n2:34:2047  -t2:EF02 ata-WDC_WD10JPVX-5555555_WXC1AA7C5555

He mentions to 'always' use the long /dev/disk/by-id aliases
though this is contrary to what Damian Wojstaw says in
"Introducing ZFS on Linux". So it is open to debate.

I'll be using that book to assist with the github steps.

then this command:
sgdisk     -n1:0:0      -t1:BF01 /dev/disk/by-id/scsi-SATA_disk1
for each hdd

next command for me:

NOTE: from guide:Make sure to include the -part1 portion of the drive path. If you forget that, you are
specifying the whole disk, which ZFS will then add another partition, then you  have to start over.

NOTE: I am NOT setting ashift, as recommended by the zfs guide. This is from the pre-mentioned book,
who recommends not setting it blindly (unless you know what you are doing - I don't). See the book for more details.

NOTE: I am also not setting acl acceleration with xattr=sa. This may be harmless, but there's
a slight chance
I will move to BSD or Solaris for fun at some point. Probably not, but I don't need the perfo
rmance increase.

if you make a mistake: zpool destroy rpool, then start over.
If necessary, you can gdisk and erase the partitions and start again.
dont use fdisk, or else youll have to add the gpt back with gdisk (invalid partition table error)

check it with # zpool status

zfs create -o canmount=off -o mountpoint=none rpool/ROOT

I'm going to skip making the datasets section, as I want one partition for root.
so only one create command:
//https://wiki.archlinux.org/index.php/Installing_Arch_Linux_on_ZFS#Format_the_destination_disk
zfs create -o canmount=noauto -o mountpoint=/ rpool/ROOT/debian

which was that
so /zpool/ROOT/debian is already mounted at /mnt

per a $ mount command
it does NOT have a lost&found folder, so it's simply blank.

though:

it is listed.

debootstrap ascii /mnt
notice it's not stretch, but ascii

and follow the rest of the steps. I had some trouble at the beginning when I used the ZFS create command on the disk and not the part1 partition (oops), but that is resolvable with gpart (and a reboot).

Worked well for me. Boots into ZFS, mirrored root devuan.

So far, so good with ZFS. I'll update if I learn anything else.