I'm trying to run a live migration of VMs between an older Dell server and a newer Dell server. While migrating from the older to the newer server works just fine, the reverse migration results in an error that says the virtual machine cannot be moved because the hardware isn't compatible. The error specifically mentions that the migration failed due to the virtual machine using processor-specific features that the older server doesn't support. I've checked that processor compatibility is enabled, and I've recently run all updates, so I'm not sure what else could be causing this issue. Could the processor compatibility mode still prevent the migration?
1 Answer
The issue you're experiencing is rooted in the specifics of CPU compatibility. You can easily migrate from an older generation CPU to a newer one since the newer CPUs generally support all the instructions from the older models. However, the reverse isn’t true; the older CPU lacks some of the instructions that may be required by the VM. That's why you're running into this error.
By the way, if you're unsure about how processor compatibility settings work, that's worth looking into!
Thanks for the detailed explanation! It's really helpful to understand why this is happening. I'm worried about the age gap between these servers—around 6-7 years. I know one supports hyper-threading and the other does not. Does Hyper-V have the capability to turn certain CPU instructions on and off, like Proxmox does?