I have an Ubuntu 16.04 Server that runs
Linux 4.4.0-187-generic #217-Ubuntu SMP Tue Jul 21 04:18:15 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux, all packages are very recent (I regularly perform standard updates). There is not much installed on that server: apt list --installed | wc -l yields 889 Packages,
and the filesystem has these partitions:
Filesystem Size Used Avail Use% Mounted on
udev 2,0G 0 2,0G 0% /dev
tmpfs 396M 26M 370M 7% /run
/dev/mapper/host--vg-root 45G 6,8G 36G 16% /
tmpfs 2,0G 88K 2,0G 1% /dev/shm
tmpfs 5,0M 0 5,0M 0% /run/lock
tmpfs 2,0G 0 2,0G 0% /sys/fs/cgroup
tmpfs 2,0G 0 2,0G 0% /run/shm
/dev/sda1 472M 133M 315M 30% /boot
/dev/mapper/host--vgdata-data1 1,8T 824G 958G 47% /data1
tmpfs 396M 0 396M 0% /run/user/1000
The system tries to convince me to upgrade to 18.04.5, but I am hesitant. I'd like to upgrade for consistency reasons, because that is the version that I have installed on a few other machines.
If the upgrade process fails I would be in trouble.
Anyone tried that specific upgrade ? (I'm asking because here someone reports problems upgrading from 14.04 to 20.04. There are more posts like this.)
Having the root partition on LVM is fairly standard and shouldn't cause you any particular problems.
However, as the previous commenters have said already, there's always a chance of something going wrong during an upgrade (packaging bug, power outage, cosmic ray, etc) so you should be prepared.