On Sat, Mar 11, 2023 at 06:35:20PM +0100, Michael Schwartzkopff wrote:

Hi,

I have an old system. The guest there is defined with:

  <os>     <type arch='x86_64' machine='pc-q35-rhel8.2.0'>hvm</type>   </os>

When I try to migrate this guest to a new system I get the error:

error: internal error: unable to execute QEMU command 'blockdev-add': Failed to connect socket: Permission denied

On the new host I see the log entries:

libvirtd[22411]: Domain id=18 name='test02' uuid=9bad33a8-d18e-4c68-bdbe-dad34142dc22 is tainted: deprecated-config (machine type 'pc-q35-rhel8.2.0') systemd-machined[9980]: New machine qemu-18-test02. systemd[1]: Started Virtual Machine qemu-18-test02. systemd-networkd[3914]: vnet20: Link DOWN systemd-networkd[3914]: vnet20: Lost carrier kernel: br1: port 3(vnet20) entered disabled state kernel: device vnet20 left promiscuous mode kernel: br1: port 3(vnet20) entered disabled state systemd[1]: machine-qemu\x2d18\x2dtest02.scope: Deactivated successfully. systemd-machined[9980]: Machine qemu-18-test02 terminated. libvirtd[22411]: migration successfully aborted

It seems there is no possible combination of machine types that is compatible for both hosts. The old host only can start rhel8.2 guests, the new one only rhel9.0.

RHEL-9 is capable of running all rhel8.x machine types, so there shold be no compatibility problems here. The message you see about deprecation is simply a warning that continuing to use this rhel8.2 machine type is discouraged, because you won't be able to live migrate it onto future RHEL-10 hosts.

Is there a possibility to change the machine type during a migration? Is such a migration possible? Or do I have so shut down the guest?

Changing machine types during live migration is impossible as that's a guest visible hardware change. That shouldn't matter foir your case though, as RHEL-9 is capable fo running rhel8.2 machine types. I'd suggeest checking the /var/log/libvirt/qemu/$GUEST.log file for details of why it might have actually failed. With regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|

Michael Schwartzkopff schrieb:

It seems there is no possible combination of machine types that is compatible for both hosts. The old host only can start rhel8.2 guests, the new one only rhel9.0.

that depends on the host, but to be honour, I don't think, that you can't use different versions of guest-os. On my Xen- and KVM-environments, we have running CentOS 5 upto 8 guests, plus some with Ubuntu. No problem with migration from one host to the other.

Is there a possibility to change the machine type during a migration? Is such a migration possible? Or do I have so shut down the guest?

I do not know that, what does the "machine type" mean? Your guest is a RHEL 8.2? If so you would have to upgrade the guest os to RHEL 9. But I think this will not solve the problem, according to the error you get "execute QEMU command 'blockdev-add': Failed to connect socket: Permission denied" it's more a problem of your new host-machine. -- kind regards, thg