KVM_Ubuntu.md

Install Ubuntu KVM to ZFS ZVOL onto Ubuntu 20.04 server

See Focal server install howto for how to install the physical machine itself.
Make sure Focal Server installer ISO is present at /tank/kvm/iso/focalserver.iso
In this examlpe 2 vCPUs, 16GB RAM and 300GB disk is used; feel free to use different values.

Create ZVOL

zfs create tank/kvm/SERVERNAME
zfs create -V 300G -s -b 128k tank/kvm/SERVERNAME/vda

Create VM

virt-install --name SERVERNAME --memory 16384 --vcpus 2 \
 --disk /dev/zvol/tank/kvm/SERVERNAME/vda \
 --disk /tank/kvm/iso/focalserver.iso,device=cdrom,bus=sata \
 --network bridge=br-eth0 \
 --noautoconsole --graphics=vnc \
 --os-variant ubuntu20.04 --boot cdrom

Open VM console and proceed with installation.
"Guided" partitioning is good enough; untick LVM since that is fultile in this case.
Set ubuntu as default user and add some password to it; enable SSH.
Get network interface MAC address and add it to DHCP.
When the installation is complete, remove the virtual CD from the VM config and reboot.

Postinstall steps

Disable "persistent interface naming" via kernel parameters:
edit /etc/default/grub and add parameters: GRUB_CMDLINE_LINUX_DEFAULT="biosdevname=0 net.ifnames=0"
then perform update-grub

Delete default network config and add simple "eth0 with DHCP":

rm /etc/netplan/*

cat <<EOF > /etc/netplan/10-interfaces.yaml;
network:
        version: 2
        renderer: networkd
        ethernets:
                eth0:
                        dhcp4: true
EOF

Reboot for get eth0 working.