Error migrating VM

bug-meister

We have a small, two-host pool, having just added a new host. The master is a Dell R640 (Intel(R) Xeon(R) Gold 6150 CPU @ 2.70GHzIntel(R) Xeon(R) Gold 6150 CPU @ 2.70GHz) and the second, an R630 (Intel(R) Xeon(R) CPU E5-2650 v3 @ 2.30GHz). I attempted to migrate a VM to the second host as a test and received the error:

"code": "VM_INCOMPATIBLE_WITH_THIS_HOST",
  "params": [
    "OpaqueRef:<UUID1>",
    "OpaqueRef:<UUID2>",
    "VM last booted on a CPU with features this host's CPU does not have."
  ],...

I don't see much other detail that seems to offer clues. How do I determine what the incompatibility actually is? If the incompatibility is determined, is there some means of disabling features to ensure capatibility?

I did try a different VM and the migration worked!?

bvitnik

@bug-meister This means that VM was running at the CPU feature level of the original host when you added a new host. For a VM to drop the CPU feature level to a level of the new host, it has to be shutdown and started again. After that, VM should be able to migrate in both ways.

The CPU feature level of a pool is determined by the CPU feature level of a host that has the lowest CPU feature level (new host in your example) but is not applied retroactively to already running VMs.

Because of these issues, it is not advisable to have pools with mixed CPU models/generations.

bug-meister

@bvitnik Thank you -- very useful information!