Inaccessible boot device hot converting VMware to Hyper-V

Matt_NZ · Mon Nov 04, 2024 10:51 pm

I'm currently using V2V converter 9.0.1.554. I'm trying to use the hot conversion/synchronize option to migrate a VM from VCenter (v7.0.3)/ESX host (v7.0.3) to Hyper-V (Server 2022, 20348.2700). When I try a hot conversion, the process succeeds but when I try boot the VM it boots to a bluescreen with "inaccessible boot device" being the error. In Vmware, the drives are thin provisioned and UEFI, so are converting to a Gen 2 Hyper-V VM. The tested VMs are running Server 2022 as well.

If I shutdown the VMs and then do a normal conversion, the VM boots fine and works as expected. I'm hoping to use the hot option for a number of large VMs that can't really afford to be offline for multiple hours/days

Tue Nov 05, 2024 8:22 am

Hi,

Welcome to StarWind Forum. Tell me more about the conversion scenario I need:
-VM guest OS.
-Did you uninstall the VMware tools before the conversion?
-Source hypervisor.
-Destination hypervisor version.

P.S. Consider running P2V inside that VM, or convert the VM disk.

Matt_NZ · Tue Nov 05, 2024 10:13 am

Thanks for the reply, I included these details in the original post but here they are again
VM Guest OS: Windows Server 2022
Source: VMware 7.0.3
Destination: Hyper-V (Server 2022)

I didn’t uninstall the VMWare tools first, but the converted VM doesn’t boot into the OS so I don’t think that’s an issue? I also didn’t remove the tools before doing a traditional conversion either which boots fine.

I haven’t tried a P2V yet, will that allow converting while the VM stays running?

Tue Nov 05, 2024 11:07 am

Many thanks for more details.
Does the VM boot in BSOD or does it fail to recognize the boot media?
P2V is run from the VM. Therefore the VM stays up throughout the conversion.
Try converting individual disks and booting up from the disk attached to the IDE controller.

Matt_NZ · Tue Nov 05, 2024 12:15 pm

I see the boot circle animation and then it jumps to a “inaccessible boot device” blue screen after a few moments. It’ll reboot into this a few time before ending up in the recovery console. This only happens with a Hot conversion - the same VMs will boot just fine if they were converted “offline”

I don’t believe IDE is a drive option for Gen 2 VMs.

Tue Nov 05, 2024 12:46 pm

Hi,

Try removing the VMware tools from the recovery mode. https://knowledge.broadcom.com/external ... g-vmw.html could be helpful.

StopFastEddie · Tue Nov 05, 2024 5:30 pm

I am having the same exact issue, with the same scenario.

Attempting to perform live conversion from VMware to Hyper-V. When I go to power up the migrated VM on the Hyper-V host, I get the Windows BSOD stating "Inaccessible Boot Device". Once I turned off the VM I can no longer get into the recovery partition.

Is there any next steps for this besides removing VMware Tools after the migration?

Tue Nov 05, 2024 7:10 pm

Recreate the VM as GEN1 and use IDE controller.

Matt_NZ · Tue Nov 05, 2024 9:02 pm

It's not possible to recreate it as a Gen 1 VM as it's setup with UEFI and GPT disks in VMware, which aren't compatible with Gen 1 VMs

StopFastEddie · Tue Nov 05, 2024 9:07 pm

Also, even if this would work, this defeats the purpose of the "hot" conversion.

Wed Nov 06, 2024 2:00 am

Can you please convert them to fixed and try converting them as thick disks?

Wed Nov 06, 2024 3:28 am

Try removing the VMware tools while in recovery mode

Matt_NZ · Wed Nov 06, 2024 6:44 am

I changed the disk to being thick provisioned in Vmware and did the migration again, with the same result. I have noticed in diskpart in the recovery environment that the main partition was marked as read only. I cleared that, but that hasn't helped.

I suppose I could attempt to recreate the bootloader and all that, but I don't want to have to do that for all 180 VMs. Tomorrow I'll remove the VMware tools and attempt it again, but I suspect that won't make a difference since it's not even getting as far as booting into Windows yet.

Wed Nov 06, 2024 12:00 pm

Please let me know how it goes.
Did you enable the safe mode in V2V UI while converting that VM?

Matt_NZ · Thu Nov 07, 2024 2:43 am

It would seem I owe an apology! My assumption that the VMware tools had no part in the issue was infact wrong. When I uninstalled the tools and then did a live migration, the VM booted just fine in Hyper-V

I'm still not sure I understand why removing the tools wasn't necessary when doing an offline migration, though!