I've upgraded from 22.04 by reinstalling Ubuntu of course. I boot my desktop from OpenZFS and I like it now! Unlike a few releases back, when Ubuntu-ZFS tried to solve all problems vaguely related to ZFS. Ubuntu 23.10 is now behaving more modest like FreeBSD and that made me happy

Today I did run my first incremental backup of say 70 VMs and it finished within 10 minutes, that made me very happy, because with 22.04 it took 1 to 2 hours. The difference; the transfer speed is now constantly between 80 and 105 MB/s, going from a desktop 2TB HDD to a laptop 2TB HDD. In 22.04 the speed dropped after some time occasionally to KB/s and even sometimes for ~10 seconds all transfers were halted. I wrote a bug report, but I already did give up on it after 1.5 year.

During the transfer to 23.10 I had problems with my 12 years old HP Elitebook 8460p (i5-2520M, 8GB DDR3), because the BIOS had a warning about using its UEFI prototype, but in the end I got it working booting from FAT32 (/boot/efi) and ext4 (/), note that all my data and VMs are stored in OpenZFS.

Finally I have the happy feeling that the desktop system is more efficient with Ubuntu 23.10; Linux 6.5 and OpenZFS 2.2, the CPU load during my normal usage dropped from ~20% to ~18%.