When you create an SDDC, you can choose to have it contain medium or large SDDC appliance configurations. An SDDC with a medium appliance configuration can be scaled up (upsized) to large. An SDDC that has a large appliance configuration cannot be scaled down to medium nor can its management cluster scale down below three hosts.

By default, a new SDDC is created with medium-sized NSX Edge and vCenter appliances. Large-sized appliances are recommended for deployments with more than 30 hosts or 3000 VMs or in any other situation where management cluster resources might be oversubscribed. Large-sized appliances are required if you want to Configure a Multi-Edge SDDC With Traffic Groups. Large-sized appliances are not supported with two-host SDDCs, single-host SDDCs, or stretched cluster SDDCs with fewer than six hosts. Large-sized appliances cannot be scaled down..

You can use a control on the SDDC Settings tab to upsize a medium-sized SDDC to a large-sized one. This change is permanent and cannot be undone. If there aren’t enough free resources available, the operation adds a host to the SDDC.

The upsize workflow includes a vCenter re-start and an NSX failover. It typically incurs 15-20 minutes of management plane downtime, and could take longer if a disk check or manual intervention is needed. During this downtime, the vCenter UI will not be available and you won’t be able to add or remove hosts or execute VM power operations. Running workloads continue to run, and vSphere HA continues to protect VMs that are already powered on. The NSX Edge failover causes a 10-15 second interruption of North-South connectivity.

Note:

This operation cannot be performed while SDDC maintenance, including the addition or removal of hosts, is underway.

Prerequisites

Verify that the SDDC has at least three hosts in each AZ that it occupies. A stretched-cluster SDDC requires at least six hosts in the management cluster (three in each AZ).

Procedure

  1. Log in to the VMware Cloud Console at https://vmc.vmware.com.
  2. On the card for your SDDC, click View Details and then click the Settings tab.
    The Settings page displays information about SDDC settings, pre-defined user accounts, and SDDC access via the API and PowerCLI.
  3. Expand the Management Appliances item under the SDDC section of the Settings tab to view or change the appliance size in this SDDC.
    If the appliance size is NSX_MEDIUM, you can click UPSIZE to open the Upsize management appliances dialog. To upsize the appliance to NSX_LARGE, select the checkboxes to confirm that you understand the consequences of your action, then click UPSIZE.
    The system displays a message to confirm that the requested operation has started and track its progress.