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UEFI vs BIOS for HyperV

    Question

  • Hi,

    We have the following:

    HyperV-A Server 2012 R2 hosting 2 VM's replicated to HyperV-B Server 2012 R2.

    Replication is fine. The issue we have is that if we startup one of the replica VM's on HyperV-B
    (obviously not at the same time as the live ones on HyperV-A), the replica fails to boot with the
    error message:

    "no uefi-compatible file system was found"

    Investigation shows that HyperV-A is using "UEFI" and HyperV-B is using "BIOS"

    So a few questions:

    1: Is the UEFI/BIOS difference the reason that the VM will not boot/start?
    2: If that is the case is there a work around?

    Cheers
    Monday, February 20, 2017 2:00 PM

Answers

  • Thanks for the replies.

    So..

    Does this then mean that if you build a VM on a host that is using UEFI, that the VM will not work on another host that is using BIOS?

    Have searched around on this and can't find much about this issue. Anyone have any further pointers on if this really is the case and if there is any official info no this issue online?

    Thanks

    • Marked as answer by Protech Online Wednesday, February 22, 2017 3:08 PM
    Tuesday, February 21, 2017 9:46 AM

All replies

  • UEFI in the guest should not be impacted by whether or not the host is configured with UEFI.  Was there anything different in the way the replica was created on Hyper-V-B?  You state 'if we startup one of the replica'.  What happens with the other replica?

    There is no real work around.  The on-disk structure for an BIOS system and a UEFI system is completely different.  The only recommended way to convert from BIOS to UEFI, or vice versa, is a complete reinstallation.


    . : | : . : | : . tim

    Monday, February 20, 2017 3:28 PM
  • Thanks for the reply:

    To put the situation another (maybe simpler way), if we create a VM on a host which is using UEFI and then we take a copy of that VM/.vhdx to another host that is using BIOS, would you expect the VM to boot up correctly?

    Like wise if we build a VM on a host using BIOS, can it run up ok on another host that is using UEFI?

    Thanks

    Monday, February 20, 2017 3:41 PM
  • Yes, I would expect the VM to work as long as the version of the hypervisor under which the VM is running supports UEFI.

    . : | : . : | : . tim

    Monday, February 20, 2017 4:07 PM
  • Thanks for the replies.

    So..

    Does this then mean that if you build a VM on a host that is using UEFI, that the VM will not work on another host that is using BIOS?

    Have searched around on this and can't find much about this issue. Anyone have any further pointers on if this really is the case and if there is any official info no this issue online?

    Thanks

    • Marked as answer by Protech Online Wednesday, February 22, 2017 3:08 PM
    Tuesday, February 21, 2017 9:46 AM
  • Does this then mean that if you build a VM on a host that is using UEFI, that the VM will not work on another host that is using BIOS?

    I never said that.  In fact, I said the opposite.  If you move a VM using UEFI to another hypervisor, and that hypervisor supports running VMs with UEFI, it should not make any difference whether the host machine was booted with UEFI or BIOS.


    . : | : . : | : . tim


    Tuesday, February 21, 2017 1:47 PM