As a preparation for the Bullseye update we need to switch the KVM machine type for the Ganeti cluster to pc-i440fx-3.1 (the "hardware" provided by qemu 3.1). Otherwise we wouldn't be able to migrate machines between Bullseye (which would default to pc-i440fx-5.0) and Buster nodes.
This requires the following steps:
[x] sudo gnt-cluster modify --hypervisor-parameters kvm:machine_version=pc-i440fx-3.1
Restart all instances of the cluster. A reboot from within the OS isn't sufficient, this needs to be rebooted on the Ganeti level so that the KVM instance gets restarted (kind of comparable to resetting a computer with the power button). There's a cookbook for this: sre.ganeti.reboot-vm FQDN
[] bast3005.wikimedia.org
[x] doh3001.wikimedia.org
[x] doh3002.wikimedia.org
[x] durum3001.esams.wmnet
[x] durum3002.esams.wmnet
[x] install3001.wikimedia.org
[x] ncredir3001.esams.wmnet
[x] ncredir3002.esams.wmnet
[x] netflow3002.esams.wmnet
[x] ping3002.esams.wmnet
[x] prometheus3001.esams.wmnet