Incompatible CPU features on live migrations

[jdias14]

Hi,

A few days ago I was migrating a VM from a PowerEdge R420 to a PowerEdge 1950 and received the following warning:

I understand that those are distinct generations of processors and since they do not support the same instruction sets it is not safe to live migrate VMs between them.

My question is: is there some kind of compatibility matrix that Xen Orchestra uses from where I can see if the migration is ging to be possible or not?

Thanks in advance.

[olivierlambert]

Hi,

It's impossible to have a matrix due to the sheer number of different CPU features for each generation. You can always migrate to "less features" to "more features", the opposite might crash your VM during a live migration. But warm migration can do it for you then.

In any case, you need to be aware of the CPU diff between pools before migrating and assert from here.

[jdias14]

@olivierlambert Ok, thanks for explanation. But then how does Xen Orchestra knows whether the destination host CPU is compatible or not?

[olivierlambert]

IIRC, XO doesn't know, it's a message coming from XCP-ng. It will compare the CPU info between source and destination.

[AlexanderK]

@olivierlambert
i have two pcs with the same cpu and i am receiving this error.
How i can check what is the issue?

migrate from

To

[olivierlambert]

You need to compare the CPU features visible on each host.

Either: compare the output of xe host-param-get uuid=<UUID> param-name=cpu_info param-key=flags on both hosts, or xl info.

[AlexanderK]

@olivierlambert
can memory size difference being showed as different cpu?
tried both commands