Mixed physical servers in cluster?

sysadm1n

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Aug 6, 2021
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I'm working in a new environment and before my time they under spec'd their vSphere ESXi host servers. Afterwards, they went and bought a few physical servers to handle heavy workloads. So they have a small virtualized environment for non-essential servers and a few mission critical physical servers. I've been running some resource monitoring tools the last few months and I've noticed those heavy spec'd individual servers are hardly using any resources. even during heavy workloads.

I'd like to slowly migrate the physical box OS's to virtual OS's and then slowly add the physical boxes to vSphere. The current ESXi hosts and the heavy spec'd individual servers are around the same age and specs i.e. similar core counts and CPU speeds (although some are intel and others are AMD). this would lead to a cluster with mixed physical ESXi hosts. I've seen this before in other environments but I've never actually questioned it... Is this common? uncommon? I'd need to upgrade the NICs in the physical boxes and get all the licensing sorted but I see this as a great way forward.

thoughts? considerations? comments?
 

Eulogy

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Nov 9, 2005
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Mixing AMD and Intel in the same cluster is generally not a good idea. In fact, I don't even think it'll allow you to add them to a single cluster (been awhile since I've played with legacy VM type stuff). At least you'll want to have an AMD cluster and an Intel cluster. You didn't really give enough info to make much in the way of suggestions on helping you. Moving to a fully virtualized stack may be the right choice.
 

sysadm1n

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Aug 6, 2021
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Eulogy Thanks for the response. You answered the primary. My question should have been can I mix AMD and Intel in one cluster. I'm not even sure the idea will fly here no matter how pretty I present it.
 

danswartz

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Feb 25, 2011
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Eulogy Thanks for the response. You answered the primary. My question should have been can I mix AMD and Intel in one cluster. I'm not even sure the idea will fly here no matter how pretty I present it.

yeah, i don't recommend that either. Even somewhat incompatible processors of the same family can be problematic, disabling live migration. And you might not even find out until you try to do a live migration.
 

Shockey

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Divide the intel and AMD CPUs servers into separate clusters if you have minimum of 3 servers per a cluster.

You may be able to turn on EVC mode and present shared storage to both clusters and try a migration?
 

danswartz

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You can do different gen CPUs you just choose the level you can migrate between. AMD to Intel, you need to shut down a VM entirely before you migrate between them. You can do 2 node clusters but you need to then create a Witness node for them also that is not hosted on the same hardware.

VMware EVC
https://docs.vmware.com/en/VMware-v...UID-03E7E5F9-06D9-463F-A64F-D4EC20DAF22E.html

maybe i am misunderstanding you, but i have a 2-xeon cluster and have no witness node, and it works fine. it is set up with datastore heartbeats (dunno if that's germane here?)
 

MrGuvernment

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Aug 3, 2004
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maybe i am misunderstanding you, but i have a 2-xeon cluster and have no witness node, and it works fine. it is set up with datastore heartbeats (dunno if that's germane here?)
Sorry, i miss-read, if using vSAN you need a witness node, if you are just using separate local storage you can do what ever you want. but with local storage and not shared storage you are not getting the benefits of seamless HA and redundancy with out having to fully migrate storage over, not just compute.

https://core.vmware.com/resource/vsan-2-node-cluster-guide
 

danswartz

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Feb 25, 2011
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Sorry, i miss-read, if using vSAN you need a witness node, if you are just using separate local storage you can do what ever you want. but with local storage and not shared storage you are not getting the benefits of seamless HA and redundancy with out having to fully migrate storage over, not just compute.

https://core.vmware.com/resource/vsan-2-node-cluster-guide
I didn't mention it because it didn't seem relevant, but I do in fact have shared storage for the cluster...
 
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