vCloud Foundation 3.5 – Scaling out the SDDC Platform

Hi everyone, this is a continuation to my earlier post vCloud Foundation and the SDDC bring-up process . In this article we will go through the scalability aspects of the platform – commissioning new hosts, expanding a Workload domain & adding additional workload domains.

You can scale the platform by adding additional hosts to the rack or by adding a new rack. A workload domain can scale utilizing hosts from the same rack or from different racks. The scalability of the platform depends upon the upper limits of vSphere and vSAN platform.

Integrated solutions like DellEMC VxRack SDDC comes as a rack scalable approach. You can have 24 hosts / rack and upto 8 racks – that means you can have upto 192 hosts / SDDC platform.

Commissioning new hosts

Before starting the commissioning process of new hosts in the SDDC manager, make sure that the hosts are installed with the appropriate ESXi version and that basic networking is configured. The wizard will start with pre-requisite guidelines and proceed only if everything is met.



You can specify the new host details either manually or by importing a json file containing the host details.


Review the settings and click finish to start the commissioning. The new hosts appear under “Unassigned Hosts” in SDDC manager.


Now these hosts can be used to scale an existing workload domain and create a new workload domain.

Scaling out a Workload Domain Cluster

Navigate to the Workload Domain cluster which you intend to scale out and under Actions, click “Add Host”



The hosts are then automatically added to the cluster. It’s added to the vSAN cluster as well as to the vSphere cluster.

Adding a new cluster to an existing Workload Domain

Navigate to the Workload Domain where you intend to create a new cluster and under Actions, click “Add Cluster”


Specify a name for the cluster


Select the VLAN ID to be used for the vmkernel port for VTEP. VTEP IP Assignment is dynamic, so make sure this subnet can get a dynamic lease from a DHCP server. Check for the DHCP relay settings on the Core switch as well.


The process will create a dvswitch and the necessary port groups for Management, vSAN, vMotion and VxLAN. The standard switch is removed from the hosts.


Select the FTT for the default vSAN storage policy for the datastore.


Select the hosts and then review the settings. Clicking on Finish will kick start the cluster deployment.




Sit back and relax until the process is completed.

Creating a new VI Workload domain

A new VI Workload Domain is a new vCenter instance leveraging the existing Platform Services Controller cluster on the management Workload Domain. It also a deploys a new NSX manager instance with 3 NSX Controller nodes (single cluster). The new NSX manager instance and the vCenter instance sits on the Management WLD. The NSX Controllers (and any future DLRs and ESGs etc) will sit on the VI Workload domain.

A VI Workload domain is where the user workloads are being run. You can have upto 15 Workload domains (including Management WLD) running in parallel. Multiple Wokload domains gives a heterogeneous environment to support multiple use cases like VDI environment, BigData clusters etc which typically leverages GPU functionality as well. In the below screenshots, I wont be deploying an entire VI Workload domain (due to lack of resources) but just puts a pointer onto how this is being done.

You can create a VI Workload domain from the Dashboard.


Select vSAN as the Storage Type



Provide the basic configuration details of the new vCenter instance that will be deployed.



Provide the basic configuration details of the new NSX manager and the NSX Controller cluster that will be deployed.



Select the FTT for the default vSAN storage policy for the datastore.


Select the hosts from the “Unassigned” list.


The process will create a dvswitch and the necessary port groups for Management, vSAN, vMotion and VxLAN. The standard switch is removed from the hosts.


Review the settings, sit back and wait for the build to complete. The process might take longer. You could see the new VI Workload domain in the dashboard.


Decommissioning hosts

Once you have deleted a VI Workload Domain or a cluster in a WLD, the hosts are released as “Unassigned” to the SDDC platform. You can repurpose the hosts only after re-imaging them – ie first decommission the hosts from the SDDC manager, re-image them, prepare them with basic configuration and then Commission them as mentioned above.


Thanks for reading.


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