Hi Gary

I am still fairly new to ACS myself, but as far as I can recall, using the 'host-passthrough' option is prone to cause problems during migrations, this is also mentioned in the documentation: https://docs.cloudstack.apache.org/en/latest/installguide/hypervisor/kvm.html?highlight=host-passthrough#configure-cpu-model-for-kvm-guest-optional I suggest changing to 'host-model' instead:

host-passthroughmay lead to migration failure,if you have this problem, you should use host-model or custom. guest.cpu.features will force cpu features as a required policy so make sure to put only those features that are provided by the host CPU. As your kvm cluster needs to be made up of homogenous nodes anyway (see System Requirements), it might make most sense to use guest.cpu.mode=host-model or guest.cpu.mode=host-passthrough

On 5/16/23 15:13, Gary Dixon wrote:

Hi everyone

Other than disabling a Pod – is there a way to prevent live migration of VM’s between Pods in ACS ?

We are on version 4.15.2 with Ubuntu 20.04 KVM hosts.  Each Pod contains a single cluster of Homogenous hosts – however there are only slight differences between the CPU’s on the physical hosts in each Cluster. We have the guest.cpu.mode set to host-passthrough but have noticed serious issues when a VM is live migrated between specific Pods (usually if a VM is started on a cluster with the slightly better CPU’s and then live migrated to an older Pod)

We have tried setting the guest.cpu.mode to host-passthrough with specific CPU features using the “guest.cpu.features=” and then setting all of the host’s CPU flags shown from the output of the lscpu command in a space separated list as instructed from ACS documentation – but we then are unable to even start a VM – insufficient resources error, - if we remove the guest.cpu.features from the agent.properties – then we can start a VM again.

It would be good if we had an option or a setting to just not allow live migration of VM’s between pods and therefore can only perform a ‘cold’ migration if we wish to move a VM to another Pod.

Any thoughts on this ?

BR

Gary


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