[PVE-User] Cluster mixed hardware behavior (CPUs)
uwe.sauter.de at gmail.com
Fri Apr 26 14:31:33 CEST 2019
To be most flexible in a HA setup you would take the minimal denominator on the CPU architecture / feature side.
E.g. if you have 5 hosts with SandyBridge CPUs and 5 Hosts with Skylake CPUs you would limit the CPU type to SandyBridge. This
enables you to migrate VMs back from a Skylake node to a SandyBridge node. Otherwise your VMs might want to use CPU features that
no longer exist after migration.
Am 26.04.19 um 14:13 schrieb Thomas Lamprecht:
> Am 4/26/19 um 2:05 PM schrieb Craig Jones:
>> To my understanding, in the vSphere world, a cluster with hosts of mixed
>> CPU frequencies and generations (let's assume consistent manufacturer)
>> will run at the lowest common denominator. In other words, if you have 3
>> hosts each with CPU frequencies being 2.1 GHz, 2.3 GHz, and 2.5 GHz
>> respectively, the entire cluster will run at a 2.1 GHz level. Is this
>> the same in the Proxmox world or what would be the equivalent behavior
>> for a Proxmox cluster?
> No, Proxmox VE does not has the GHz logic VMWare products have.
> You add cores to the VM, the VM can use that, if you want to reduce
> total CPU usage you can set CPU limits, with this you could add 4 cores
> to a VM but limit it to use maximal 200% (which could be all 4 cores at
> 50%, or 2 at 100%, ...)
> For this, and various other reasons, we recommend homogeneous nodes in
> a cluster, while differences to a certain degree do not really matter,
> having a very asymmetrical (e.g., a 10 year old quadcore and a new
> 48-core CPU) setup makes things not easier.
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