Hey. 

Here is a graph from one of our clusters. 3 control nodes. 34 hypervisors, some 900 VMs. 7 days average. Grey tone is after hours for us. 

We have a 25Gb network, with 40Gb uplinks. iSCSI for storage, those iSCSI graphs look very different during back up time and when Delphix is doing a data push, but the control nodes are pretty happy and mostly under 1Gb. 

image.png

I wouldn't want to run this cluster on 1Gb switches, but the size of the cluster matters. While our control nodes are pretty happy at about 1Gb for this specific cluster size, it's going to depend on your setup and importantly the overall size. When Delphix does a refresh, we can see 40Gb line rate on the uplinks for about 6 hours during that refresh, but that is not on the control nodes, those are storage networks. 

Cheers. 
Michael, 

On Tue, Jul 9, 2024 at 8:38 AM Danny Webb <Danny.Webb@thg.com> wrote:
 I think this very much depends on your architecture, workload, deployment and ultimately your requirements. 

Where are you deploying the network nodes (or are you using DVR)?
How much north / south traffic will your environment use?
What do you mean by storage nodes (eg, cinder volume workers or actual lvm / ceph storage nodes)?
How big are your Glance images going to be and how many VMs will be built concurrently?
Where are you storing your glance images?

I'm sure openstack can run using 1G networks, it's just a question of will your deployment meet your performance 
requirements.
From: William Muriithi <wmuriithi@perasoinc.com>
Sent: Sunday, July 7, 2024 20:35
To: openstack-discuss@lists.openstack.org <openstack-discuss@lists.openstack.org>
Subject: Network demand for controller nodes
 

CAUTION: This email originates from outside THG

Hello,

Does anyone know if controller nodes are demanding on network needs?  I have a situation where I don't have enough 10GB/s port in the switch.

Would a cluster be network constrained if I have three controllers using 1GB/s connections and the execution and storage nodes are on 10GB/s connections?   Does the VM traffic ever transverse the controller's network cards?

In another word, is there a valid requirement for 10GB/s on openstack controllers?

Regards,
William