When do you expect that persistent L2ARC will come to Ubuntu or Debian?
Do you know if it will be possible to upgrade existing ZFS pools?
(I have a ZFS with a lot of scientific data and dedupe that could benefit from it.)
Thanks a lot for your advice! 
Not completely. Still in the release candidate stage.
But once 2.0 ships it should be nice.
It takes a while to filter through to some distro’s.
This is a Distro /Linux problem, not Openzfs.
Workaround is to use Pure Sauce from GitHub, rather than package managed urial/tools
Yeah, not to be that guy, but I use Gentoo btw and it’s already in the portage repos so I was assuming it was out out. I guess it makes sense with this being a pre-release
I was commenting from a position of eternal slight frustration, running a slower cycle distro means it takes a whole for things to filter through.
OP asked about Debian and Ubuntu, (I use Ubuntu) specifically because they release later…
Does anyone know if persistent L2ARC will get into Ubuntu 21.04?
if you have zfs v2.0.0 or higher… you should have it
Update: Open ZFS 2.0 is incomming for 21.04 on April
Haven’t messed with it myself, but it looks like you’ll also have to manually enable persistent L2ARC: https://reddit.com/r/zfs/comments/lwgh06/_/gphen4j/
mercenary_sysadmin wrote:
…you may need to set a kernel tunable for persistent L2ARC. I haven’t played with this yet, but I believe this is how you’d set it, in /etc/modprobe.d/zfs.conf (assuming OpenZFS on Linux):
options zfs l2arc_rebuild_enabled=1
On FreeBSD, you set the option in /etc/sysctl.conf:
vfs.zfs.l2arc.rebuild_enabled=1
You’d need to reboot (or otherwise export and re-import the zfs kernel module) after making the change.