VMware Integrated OpenStack – Collapse Compute & Edge Clusters

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VMware Integrated OpenStack (VIO) introduced the ability to deploy to multiple vCenter Servers with version 2.5. The feature allowed the OpenStack management VMs to be deployed inside a control plane vCenter, while allowing the data plane to use a separate vCenter server. The architecture model still required three clusters:

  • Management Cluster (Management vCenter Server)
  • Compute Cluster(s) (Workload vCenter Server)
  • Edge Cluster (Workload vCenter Server)

The three cluster architecture follows the published best practices from both VIO and NSX. Having a dedicated Edge cluster should free up tenant resources and prevent potential issues with network noisy-neighbors. However, having a dedicated cluster just for NSX Edge VMs could be overkill in some environments from both a cost and compute perspective. If you are also using Virtual SAN to leverage hyper-converged infrastructure (HCI), the cost increases considerably with licensing costs for vSphere, NSX and Virtual SAN for hosts that will be extremely under-utilized.

So how can you collapse the compute and edge clusters in a VMware Integrated OpenStack environment?

In version 3.0 there is a configuration change that makes it possible to collapse these two cluster. Performing the following steps will allow you to deploy a smaller footprint OpenStack deployment using VIO.

$ sudo vim /opt/vmware/vio/etc/omjs.properties

Add the following lines to the end of the configuration file:

## Collapse the Edge/Compute clusters
oms.allow_shared_edge_cluster = true

Restart the OMS services
$ sudo restart oms

Once the OMS services have been restarted, the VIO Deployment UI will now allow you to deploy the Edge VMs inside the same Compute cluster on the control plane vCenter Server instance.

A couple caveats to this approach to be aware of:

  • All tenant deployed Edge VMs will live in the collapsed Edge/Compute cluster. As the environment scales to include multiple compute clusters, only this initial Edge/Compute cluster will have the Edge VMs.
  • The OpenStack Horizon UI is unaware of these tenant deployed Edge VMs, so reporting on utilization within the compute cluster is shown on the screen, the rates will have discrepancies — depending on how large the environment is.

Your mileage may vary, but this option allows for some additional flexibility when deploying VMware Integrated OpenStack.