CPU architecture: Live Migration vs Quick Migration vs Storage Migration

Question

Hi,

I'm trying to figure out this Live Migration vs Quick Migration vs Storage Migration thing. I know that LM needs to have similar CPU and the same manufacturer. What about QM and SM?
The other thing is processor compatibility. Does this apply to LM only or all? I understand that by using import-vm/export vm we can bypass this.

Answer 1

Live migration depends upon the same hardware instruction set to be used on both systems. If using different version processors from the same manufacturer (Intel to Intel and AMD to AMD), it is possible to limit the instruction set used by specifying that the VMs be run in processor compatibility mode. This ensures a base instruction set is used for both. This is required for live migration because the actual memory of the running VM is transferred to the second machine.

Storage migration is not concerned with transferring memory - just storage. However, if transferring the system disk from one system to another, and you are employing live migration at the same time, then you have the constraints of live migration. But if you are just transferring the location of a data disk from one location to another without moving the running VM, you don't have to worry about processor compatibility.

https://social.technet.microsoft.com/Forums/windowsserver/en-US/e17cdb0e-150d-4486-a873-34c56ceea848/difference-between-quick-and-live-migration from the old forums provides a good comparison between live and quick migration.

Answer 2

Hi,
Both live migration and quick migration are impacted by the processor compatibility mode. This applies to any virtual machine mobility scenario that does not involve rebooting the virtual machine. These include virtual machine live migration, save and restore, and production checkpoints.
With processor compatibility mode enabled, Hyper-V only exposes the guest VM to processor features that are available across all processors of the same processor architecture. If it's not enabled, you'd shut down the VM before migration or exporting VM.

For more details you could refer to this article
https://learn.microsoft.com/en-us/previous-versions/windows/it-pro/windows-server-2012-r2-and-2012/dn859550(v=ws.11)

Best Regards,
Ian

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