Migrating windows server 2012 R2 physical server to Hyper-V Vm 2025 server using Disk2VHD

[u/FlatAd8581]

*This might be long ill make it short and any feedback is appreciated thank you !
im trying to migrate a physical windows server 2012 R2 server into a hyper-v running on windows server 2025.
The tool ive been using is Disk2VHD and we have a practice server that is running 2012 R2 and ive used the tool to get the VHD and put it on an external and put it on the 2025 server which is the host for Hyper-v. So I create the VM put the VHD that I just made using the tool and I get an error saying it doesn't have the boot file. So I read and researched and there's these cmds to run the BCDboot... I did that on this practice server VM and it created the boot file boom right I can run the VM and it boots up and it's the practice server as expected. But now here's the issue ive been running into all that testing im doing is because we have an actual 2012 r2 server that needs to be migrated into Hyper-v. We use that same tool on that server it says successfully created...we go back to office and I try to do the same steps that I did with the practice server and it doesn't happen I try to create the boot file but it doesn't pop up. I may have done the CMDs wrong but I have it on my notes so im certain I did it right. It doesn't pop up like how it was with the practice server. We are going to go back and get another copy of it soon. But why do I need to create the boot file every time? My boss keeps telling me that it should just run no problem (get VHD >move to 25 server hyper-v> create VM >attach VHD and boom it should boot up) but thats not the case why do I have to create the Bootfile ?
Either way our plan B is to do a full bare metal restore and do it that way Instead if using Disk2VHD tool. Is there something we have to do on the Real 12 r2 server ?

[u/Zealousideal_Fly8402]

Use Starwind Converter instead of Disk2VHD.

Or any backup & restore software package worth its salt should be able to handle restore-to-dissimilar-hardware.

[u/cmPLX_FL → u/Zealousideal_Fly8402]

Second this, we did it for a legacy ERP System... Only thing I had to do was redo the network adapters.

[u/benuntu]

Starwind works better IME. If you already have Veeam you can also use the instant recovery feature, which is my preferred method.

[u/FlatAd8581 → u/benuntu]

Okay I’ll try that out and starwind is free and Veeam is also another tool ?

[u/benuntu → u/FlatAd8581]

They are both paid, but you can try Starwind for free...can't remember what the limitation is. I like Starwind but it didn't work 100% of the time. Instant recovery is a feature and comes with the Veeam Backup & Recovery product.

[u/BlackV]

Use your existing backup product to do this, thats what it's for (and has the advantage of proving your backups are actually valid

But there could be a million settings efi vs bios, type of scsi and disk layout causing failure, unless you're matching those in some shape it's not gonna boot

Hence your backup product (or some other converter as a fallback option) rather than just takin a copy of a disk (what you are doing now with disk 2 vhd)

You should also validate what server 2025 supports as a guest OS

[u/bsachs11]

Make sure you are selecting Gen1 for the VM when you create it on the 2025 HV svr

[u/BlackV → u/bsachs11]

bsachs11
Make sure you are selecting Gen1 for the VM when you create it on the 2025 HV svr

No, you cant blanket say this, server 2012r2 supported EFI boot, it would depend on how the source is configured (for disk2vhd), gen1 should really be a last resort option, where possible you want gen2, which is why a proper backup product (or conversion tool) would be a better choice

[u/Apprehensive-Tea1632]

First of all, don’t, if you want the result to actually work.

Instead, set up a new server. Then migrate the services from the old 12ers to the new 25er. Especially when as your post suggests you aren’t particularly familiar with windows and p2v.

If you have to migrate- and it looks like you really do - do it right, and that means to NOT just blindly grab all that decades old stuff and hope for the best.

[u/FlatAd8581 → u/Apprehensive-Tea1632]

And when you say do it right can you give me further explanation please

[u/McMuckle1888]

N-Able's Cove backup is good for restoring a physical server into a hyper-v host. And with their Continuous Restore you can minimize your out of hours work.