Well, Ubuntu 23.04 is here and it's time for the new round of ZFS encryption
testing. New version, minor ZFS updates, and slightly confusing numbers at some
First, Ubuntu 23.04 brings us to ZFS 2.1.9 on kernel 6.2. It's a minot change on
ZFS version (up from 2.1.5 in Ubuntu 22.10) but kernel bump is more than what we
had in a while (was kernel 5.19).
Good news is that almost nothing has changed as compared to 22.10. Numbers are close enough to what
they were before that they might be a statistical error when it comes to either
AES-GCM or AES-XTS (on LUKS). If that's what you're using (and you should), you
can stop here.
However, if you're using AES-CCM, things are a bit confusing, at least on my
test system. For writes, all is good. But when it comes to reads, gremlins seem
to be hiding somewhere in the background.
Every few reads speed would simply start dropping. After a few slower measurements,
it would come back where it was. I repeated it multiple times and it was always
reads that started dropping while writes would stay stable.
While that might not be reason not to upgrade if you're using AES-CCM, you might
want to perform a few tests of your own. Mind you, you should be switching to
As always, raw data I gathered during my tests is available.