Hi, is it also problematic migrating to different CPUs of same Family? For example from Epyc 9654 to Epyc 9754 ?
So you recommend to make a cluster for each CPU Type ? Can you define the migration peer for hosts? For example having them all one cluster but define somehow that migration should be done between hosts of same CPU? BR -----Original Message----- From: Guto Veronezi <[email protected]> Sent: Mittwoch, 10. April 2024 00:14 To: [email protected] Subject: Re: CPU compatibility Hello Steve, For CloudStack, it does not matter if you have hosts with different processors; however, this is a recommendation regarding how virtualization systems work; therefore, this discussion happens aside from CloudStack. When we are dealing with different processors, we are dealing with different flags, instructions, clocks, and so on. For processors of the same family, but of different generations, we can level the instructions to the lowest common denominator (limit the instructions to the older generation); however, it starts to get tricky when we are dealing with different families. For instance, if you deploy a guest VM in a host with Xeon Silver and try to migrate it to a Xeon Gold, the OS of your guest, which already knows the Xeon Silver instructions, might not adapt to the instructions of the new host (Xeon Gold). Therefore, in these cases, you will face problems in the guest VM. If you are aware of the differences between the processors and that mixing different types can cause problems, then you can create a cluster mixing them; however, it is not recommended. For KVM, the parameter is defined in ACS; on the other hand, for XenServer and VMware this kind of setup is done in the cluster in XenServer or vCenter. It is also important to bear in mind that, even though you level the instruction sets between the different processors in the host operating system, you might still suffer some issues due to clock differences when you migrate a VM from a faster CPU to a slower CPU and vice versa. Best regards, Daniel Salvador (gutoveronezi) On 09/04/2024 18:58, Wei ZHOU wrote: > Hi, > > You can use a custom cpu model which is supported by both cpu processors. > > Please refer to > https://docs.cloudstack.apache.org/en/latest/installguide/hypervisor/k > vm.html#configure-cpu-model-for-kvm-guest-optional > > -Wei > > > On Tuesday, April 9, 2024, S.Fuller <[email protected]> wrote: > >> The Cloudstack Install Guide has the following statement - "All hosts >> within a cluster must be homogenous. The CPUs must be of the same >> type, count, and feature flags" >> >> Obviously this means we can't mix Intel and AMD CPUs within the same >> cluster. However, for a cluster with Intel CPUs, how much if any >> leeway is there within this statement? If I have two 20 Core Xeon >> Silver 4316 CPUs on one host and two 20 Core Xeon Silver 4416 CPUs >> in another, is that close enough? I'm looking to add capacity to an >> existing cluster, and am trying to figure out how "picky" Cloudstack is >> about this. >> >> >> >> Steve Fuller >> [email protected] >>
