Right now I'm using zfsonlinux on Fedora 19, and it works excellently. Mounting works at bootup as planned using the initscript (included with zfs) that systemd calls, but there's a pretty significant flaw: ZFS is mounted way, WAY too late during boot, to the point that transmission and other services get very lost without /zfs mounted and can't recover, hence failing them.
What I'm after is a way to get systemd to fire up the script before doing anything else. I know how to do it using initscripts (just set it to a lower runlevel, say 2), but I haven't the foggiest when it comes to doing it with systemd's target system.
I've tried setting things in the services that require zfs to be up, but it doesn't work, barring Type=idle (but there must be a better way of doing it regardless):
Requires=network.target After=zfs Type=idle
And for reference's sake, here's the initscript provided by Fedora. Due to the nature of how ZFS mounts on linux (?), I can't just plop an entry into fstab and be done with it, it has to be mounted using commands.