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MarcusBuettemeyer asked YuhanDeng-MSFT commented

Server Backup and Hyper-V discrete device assignment (DDA)

I recently attached a Wi-Fi card to a W10 VM "LabWD1" on a 2019 host using DDA. Now I always get warnings when running Windows Server Backup, stating that the virtual computer LabWD1 could not be backed up.

Is this expected behavior or am I doing something wrong? The Wi-Fi card works like a charm in the VM.

Also: since there are no errors backing up the volume where the VM's files are located, I assume there should be no big issues restoring the VM, except maybe having to manually import it into Hyper-V. Is that correct?

Any insights would be greatly appreciated.

windows-server-hyper-vwindows-server-backup
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YuhanDeng-MSFT avatar image
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YuhanDeng-MSFT answered YuhanDeng-MSFT edited

Hi Marcus,
For deploying DDA,hope this will help:
https://docs.microsoft.com/en-us/windows-server/virtualization/hyper-v/plan/plan-for-deploying-devices-using-discrete-device-assignment
And in this case,when you receive the warnings,is there any event id or error code relevant to this issue?That would help us better determine the cause. If possible,please provide us with the certain error code or event id.

Thanks for your understanding.
Best regards,
Danny


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MarcusBuettemeyer answered YuhanDeng-MSFT commented

Indeed, I get Event ID 19560 "Cannot perform the operation for 'LabWD1' as that virtual machine has one or more devices assigned to it." This seems to clear up the first part of my question: it's expected behavior.
I also get Event ID 18016 "Production checkpoints cannot be created for 'LabWD1'." even though the VM has standard checkpoints configured, so that seems to be the issue here.

The second question remains, though: what are the implications when restoring the VM? Any ideas?

Thanks for pointing me in the right direction!

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Update: It seems that restoring the backup will work. It presents the backup as an option when importing. I couldn't do an end-to-end test, since I did the restore on a different Hyper-V host which lacks the DDA PCIe device but it looks like it should work, maybe after manually connecting the DDA device. I for one am confidant that a manual restore should work.

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Hi Marcus,
Thanks for your feedback. Please do make sure that you make copies if you have significant data.
And let's see what happens.

Best regards,
Danny

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Update2: It seems that the warning only appears, when the DDA-Guest is saved or shut down. If the VM is running normally, there are no warnings. Probably has something to do with Online vs. Offline backups...

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Hi Marcus,
I did some research trying to find related documents about the differences between online and offline backup,but it seems that most of the documents are provided by third party websites. Maybe you will need to check them and see if they're related to this issue.

Thanks for your understanding.
Best regards,
Danny

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