With VxRail version 4.7.300 or later, you can join an existing SSO domain during first run. This feature allows for two VCF on VxRail management WLDs to join the same SSO domain, and it must be configured during the deployment of the second VCF instance. This configuration provides a single view for the management and WLD vCenter instances at each site. Important factors to consider include:
- vCenter instances for each VCF instance that participates in the same SSO Domain are connected using Enhanced Link Mode (ELM).
- Maximum number of WLDs is reduced by half.
- Total of 15 WLDs can be shared across the 2 VCF instances. This limitation is due to the maximum number of vCenter instances that can be connected with ELM.
- Replication configuration should be in a closed-loop design.
- Manual configuration is required to point Site2 back to Site1.
Figure 59. Shared SSO Domain topology for two VCF instances
Future upgrade considerations
Some factors that must be considered when it comes to upgrading a VCF multi-instance shared SSO domain deployment. The system administrator must use caution when upgrading VCF instances that are part of the same SSO. Consider the following guidelines before an upgrade of the VCF instances:
- Keep all VCF instances in the same SSO at the same VCF on VxRail version.
- Perform upgrades on each VCF on the VxRail system in sequential order.
- Ensure that all VCF instances in the same SSO are at N or N-1 versions.
- Do not upgrade a VCF instance that would result in having a participating VCF instance at an N-2 version.
- The compatibility rules in VCF LCM do not extend to external VCF instances.
There are no safeguards that would prevent you from upgrading one VCF instance that would break compatibility between the components participating in the shared SSO domain.