Configure the Deployed SDDCs

After deploying the Software-Defined Data Centers (SDDCs) in OCI Dedicated Region A and OCI Dedicated Region B, several Day 2 configuration steps are required to prepare for the upcoming VMware vSAN stretched cluster configuration, which will be performed in a later section.

Update Host File on Bastion VMs

To avoid dependency on DNS services during early configuration, update the /etc/hosts file on each Bastion VM in both regions with the fully qualified domain names (FQDNs) of the vCenter Servers and NSX Managers.

While FQDN resolution is already available within the OCI environment through OCI Private DNS, statically defining these entries ensures consistent access to SDDC management interfaces even if DNS configurations are incomplete or unavailable during transitional states.

Reconfigure Secondary Site - OCI Dedicated Region B

Upon SDDC deployment, all management components in OCI Dedicated Region B will reside in the vSphere-TEMP VLAN. Perform the following operations in the VMware vCenter of OCI Dedicated Region B:

  1. Migrate Management VMs
    • Consolidate all VMware management VMs to a single VMware ESXi host.
  2. Change Storage Policy
    • Update the storage policy of all management VMs to Management Storage Policy - Single Node.
  3. Prepare Hosts
    • Disable HA and DRS.
    • Place all remaining VMware ESXi hosts (except the one hosting management VMs) into maintenance mode using the Ensure Accessibility option.
    • Remove these hosts from the VMware vSAN cluster.
    • Remove them from VMware NSX via the OCI Dedicated Region B VMware NSX Manager.
    • Disable lockdown mode, and enable SSH and ESXi Shell access.

Reconfigure Primary Site - OCI Dedicated Region A

In the VMware vCenter of OCI Dedicated Region A, complete the following steps:

  1. Disable HA and DRS
    • Temporarily disable HA and DRS in the existing cluster.
  2. Create and Prepare Cluster
    • Create a new cluster for hosting both local and incoming cross-site ESXi hosts.
    • Place all hosts (except the one with management VMs) into maintenance mode.
    • Remove them from the VMware vSAN cluster and move them to the newly created cluster.
  3. Add OCI Dedicated Region B Hosts to OCI Dedicated Region A New Cluster
    • From OCI Dedicated Region VMware vCenter, add the OCI Dedicated Region VMware ESXi hosts by FQDN.
    • Add these hosts to the newly created cluster and remove them from maintenance mode.

Consolidate and Update Distributed Virtual Switch (VDS)

Now that all ESXi hosts across both Primary Site and Secondary Site are managed by the same VMware vCenter inOCI Dedicated Region A:

  • Use the existing VDS from Primary Site (OCI Dedicated Region A) as the unified distributed switch.
  • Recreate all Secondary Site (OCI Dedicated Region B) port groups (PGs) on this Primary site VDS to ensure consistency and compatibility.

The VDS configuration must now support four uplinks: two uplinks from Primary Site hosts and two from Secondary Site hosts.

Configure Teaming and Failover Policies

Site Active Uplinks Standby Uplinks
Primary Site PGs Primary Site vmnic0, vmnic1 Secondary Site vmnic0, vmnic1
Secondary Site PGs Secondary Site vmnic0, vmnic1

Primary Site vmnic0, vmnic1

Important: For the Management Port Group (vmk0), use only vmnic0 specific to the host’s site (i.e., vmnic0 from Primary Site for Primary Site hosts, and from Secondary Site for Secondary Site hosts). This matches Oracle Cloud VMware Solution deployment behavior, where only vmnic0 connects to the backend Management VLAN.

This configuration ensures that traffic will gracefully fail over to the Secondary Site uplinks if Primary Site hosts become unavailable, maintaining uninterrupted connectivity across the cluster.

Once the Secondary Site port groups have been recreated on the unified VDS:

  • Validate VM and host connectivity across all port groups.
  • Ensure all VDS port groups and VMkernel interfaces (vmk) are configured with MTU 9000, which usually defaults to 1500 and must be explicitly updated.

Finally, remove the legacy VDS configuration from Secondary Site hosts to avoid conflicts.

Migrating vmk0 to the Unified VDS

Note:

In some cases, migrating vmk0 (Management interface) from its existing configuration to the new VDS may fail and roll back. If this occurs:
  • Log in to the host via SSH.
  • Run dcui to launch the Direct Console User Interface (DCUI).
  • Restore network settings to move vmk0 to a Standard vSwitch (VSS).