Migrating a KVM guest to different architecture CPU

Obsolesce

I transferred my KVM VM from my desktop with a Xeon, to a laptop with an i7. No issues or anything at all really.

Obsolesce

Both running Fedora KVM/QEMU

black3dynamite

The only time I had issue is if i was moving between AMD and Intel. When that happens I normal use qemu or kvm cpu models.

JaredBusch

Yeah, thanks. I did not expect any issues, but have not done it previously.

Obsolesce

@jaredbusch said in Migrating a KVM guest to different architecture CPU:

Yeah, thanks. I did not expect any issues, but have not done it previously.

The only difference between how I did it, and how it looks like you are doing it... is that I haven't used the same XML.

I set it up again from scratch, only re-using the virtual disk.

There may be a setting in your XML pointing to your old CPU config, but I don't know... just a guess.

JaredBusch

@tim_g There is. I'll post that in a moment.

JaredBusch

The qcow2 is transferring at a good clip.

0_1514527114328_6841e102-19e9-4428-8790-41df8ac6bf40-image.png

JaredBusch

@jaredbusch said in Migrating a KVM guest to different architecture CPU:

@tim_g There is. I'll post that in a moment.

Export of plex.xml form the original box has this.

  <cpu mode='custom' match='exact' check='partial'>
    <model fallback='allow'>Nehalem</model>
  </cpu>

Export of a test Fedora 26 system on th enew box has this.

  <cpu mode='custom' match='exact' check='full'>
    <model fallback='forbid'>SandyBridge</model>
    <feature policy='require' name='vme'/>
    <feature policy='require' name='hypervisor'/>
    <feature policy='require' name='arat'/>
    <feature policy='require' name='xsaveopt'/>
  </cpu>

So it is different. But I am going to try it. Tomorrow morning once the copy of the qcow2 is finished.

I will have to edit the XML to point to the new location of the disk.

JaredBusch

Imported the XML with only the network and disk lines edited appropriately, and it booted right up.

As awesome as expected.

black3dynamite

@jaredbusch said in Migrating a KVM guest to different architecture CPU:

Imported the XML with only the network and disk lines edited appropriately, and it booted right up.

As awesome as expected.

That’s the one thing I missed about hyper-v 2012 having the ability to edit xml files.

JaredBusch

@black3dynamite said in Migrating a KVM guest to different architecture CPU:

@jaredbusch said in Migrating a KVM guest to different architecture CPU:

Imported the XML with only the network and disk lines edited appropriately, and it booted right up.

As awesome as expected.

That’s the one thing I missed about hyper-v 2012 having the ability to edit xml files.

I have manually migrated VMs with Hyper-V using the export and import method, which would match what I did here from a technical standpoint.

But as I used the Hyper-V Manager GUI to do everything, I never even looked to edit a file directly. In that case, the disks was imported from where it was saved instead of being copied directly. I did have to edit the VM settings on the new instance to attach the correct network.

The Hyper-V export process does create files and I assume one can edit them as I did here.

Obsolesce

@jaredbusch said in Migrating a KVM guest to different architecture CPU:

@black3dynamite said in Migrating a KVM guest to different architecture CPU:

@jaredbusch said in Migrating a KVM guest to different architecture CPU:

Imported the XML with only the network and disk lines edited appropriately, and it booted right up.

As awesome as expected.

That’s the one thing I missed about hyper-v 2012 having the ability to edit xml files.

I have manually migrated VMs with Hyper-V using the export and import method, which would match what I did here from a technical standpoint.

But as I used the Hyper-V Manager GUI to do everything, I never even looked to edit a file directly. In that case, the disks was imported from where it was saved instead of being copied directly. I did have to edit the VM settings on the new instance to attach the correct network.

The Hyper-V export process does create files and I assume one can edit them as I did here.

As of HyperV 2016, you can no longer edit the files directly. Not xml anymore.

Obsolesce

I forget their reason for doing so, but i remember it made sense.

black3dynamite

@tim_g said in Migrating a KVM guest to different architecture CPU:

I forget their reason for doing so, but i remember it made sense.

Corrupted config files was one of the reason.