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SOLVED Hyper-V issues - CPU cores/threads

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Benching Team Leader
Jan 2, 2005
At work we have small test server with Server 2012R2 / Hyper-V and couple of VM and all was working fine for about 6-7 months. I'm not sure when but after some updates one of the VM is showing error and I can't find any way to turn it on using more than 1 CPU core/thread.

Host is working on 5820K so 12 threads in total. 3 VM are less important and had always 1 thread.
1 VM had 4 threads and was working like that for 2 months 24/7 but now it's impossible to turn it on as there is always error.
When I try to set new VM there is only 1 thread as an option in settings.

I can't find any info on MS sites about that error.
I also can't find info when this error had happened. 4-5 colleagues are using it too and I have no idea when or who accepted windows updates. +/- 2 months so searching in logs can take some time.

Maybe anyone has any ideas how to fix it ?




Solved. Stupid windows update error. OS locked CPU at 1 core. Shutting down everything and restarting server helped.
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