For site disaster scenarios and maintenance needs, multiple sites are used to implement geographic redundancy, which ensures that a secondary site can be used to complement the primary site.
Redundancy Choice |
Design Considerations |
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Singe Site |
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Active-Standby |
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Active-Active |
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Availability Zones
Redundancy can be built in a single site to protect against power outages, for example. However, this design choice comes with duplicate hardware cost overhead. This design is out of scope of this reference architecture.
By design, multiple availability zones belong to a single region. The physical distance between the availability zones is short enough to offer low, single-digit latency and large bandwidth between the zones. This architecture allows the cloud infrastructure in the availability zone to operate as a single virtual data center within a region. Workloads can be operated across multiple availability zones in the same region as if they were part of a single virtual data center. This supports an architecture with high availability that is suitable for mission-critical applications. When the distance between two locations of equipment becomes too large, these locations can no longer function as two availability zones within the same region and must be treated as multi-site design.
Multi-Region
Multiple sites support placing workloads closer to the CSP's customers, for example, by operating one site in US Northern California and one site in US Southern California. In this multi-site design, a secondary site can become a recovery site for the primary site. When components in the primary site become compromised, all nodes are brought up in the failover site.
VMware vSphere Replication is used to replicate VM disks from the primary to the secondary site. In case of failure, the Resource Pod workloads can be brought up on the secondary site and routing updated to divert subscriber traffic to the secondary site.
Though the state and database configuration for VMware Integrated OpenStack are replicated similarly, the control plane functions of VMware Integrated OpenStack need to be updated manually. For more information, see the VMware Integrated OpenStack Administration guide.