Hello everyone,
May I ask - for a KVM virtualization host with running multiple guests, if I update the host from (e.g.) AL 9.4 to AL 9.5 , it involves a number of packages, including:
Do I need to shutdown all KVM guests before dnf update ?
or simply let the guest running during dnf update, then shutdown guests, and reboot?
Thank you very much for your advise
Regards
George
First, update of glibc is something that does not come to (full) effect before reboot – the currently running processes continue to have the old glibc in memory, even though the files are replaced.
Hence one could assume that running processes keep running, until stopped. Naturally, programs that keep (re)loading their files (plugins, etc) on some actions – e.g Emacs, Firefox – will crash. The kvm – not sure, but somewhat confident – is not like that.
Some (service) packages restart the service on package update. The sshd does, but that does not kill existing sessions. So, the restart of libvirtd might not affect the VMs.
Then again, as counter-example, after updating NVidia’s proprietary drivers its ‘nvidia-smi’ tool can no longer talk to the driver in memory due to version mismatch.
A lot of words to hide that I don’t know for sure.
I had a luxury of two hosts and setup that did allow live migration of all VMs to one host for the duration of the update of the other host. I have lost that and now I shut down the guests for the duration of the host updates. The way I see it, one either can afford (redundant) hosts, or the bit longer guest downtime.