Renew servers - Switching from Intel to AMD Epyc - advice needed

TwiX

Renowned Member
Feb 3, 2015
310
21
83
Hi,

I have lots of old Dual CPUs Intel servers and I plan to renew them.

Seems that AMD Epyc are now competitive (costs and performance).

What I'm about to build :

4 x Supermicro nodes, with per node :
1 x AMD Epyc 9534 (64 cores/128 threads)
512 GB RAM
2 basic SSD with RAID1 for OS
4 nvme write intensive disks (1.6TB/disk) for Ceph
4x25 Gb SFP28 network card

99% of my VMs are KVM based with the following settings : 2 sockets / 3 cores ( 6 cores total) and CPU type 'host' - Numa enabled
90% of these VMs run Linux / 10% Windows

Ok so my question is :
Should I expected some issues related to new AMD Epyc CPUs when migrating ?
shutdown VM => backup VM to a PBS server => restore VM as it is to the new AMD cluster

Should I have to change CPU VM settings ? ( 1 socket / 6 cores instead of 2 sockets / 3cores)
Do I have to disable NUMA (because of new nodes will only have one physical CPU) before restoring the VMs ?

IFAIK, nothing has been compiled inside VMs.

Thanks in advance!

Antoine
 
Should I have to change CPU VM settings ? ( 1 socket / 6 cores instead of 2 sockets / 3cores)
Do I have to disable NUMA (because of new nodes will only have one physical CPU) before restoring the VMs ?
Normally AMD had multiple NUMA nodes on one CPU due to the chiplet design for many years now. Check numa before changing the VM configuration.
 
Thanks
I just made a test with my ryzen 5 5600U (6 cores / 12 threads) homelab
Code:
root@prox:~# numactl --hardware
available: 1 nodes (0)
node 0 cpus: 0 1 2 3 4 5 6 7 8 9 10 11
node 0 size: 31505 MB
node 0 free: 7719 MB
node distances:
node   0
  0:  10


I restored a Windows 2019 server (originaly from a Dual Intel Xeon Silver 4210)
And keep the VM as it was.

It just works :)
Windows server seems also still activated even with new CPU detected.

So I guess I won't get any pb
 
Windows server seems also still activated even with new CPU detected.
Normally, if you don't change anything, the CPU is already of type KVM processor, which is already virtualized. From the point of the VM, the CPU is the same and has not changed at all. If you use cpu: host, it'll be noticed.
 
Hi,

yes you're right, as I mentioned I always use CPU type=host.
This is the reason why I expected bad situation for all my activated Windows VMs.

Indeed, after restoring my VM to my homelab, Windows shows the new cpu model. Fortunately, there is no need to reactivate Windows :)
 

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