Simple active/active replication
In an simple active/active replication topology, two HCP systems replicate the same HCP tenants and namespaces and default-namespace directories to each other over an active/active link. The items being replicated can be created originally on either system. The items are read-write on the system in which they were created and, after being replicated, are also read-write on the other system.
With active/active replication, client requests can be directed to either system. All changes made on each system, including both configuration changes and changes to namespace content, are replicated to the other system.
What this looks like
The following figure shows a simple active/active replication topology in which two HCP systems (A and B) are replicating to each other.

In this figure:
- Two of three HCP tenants created locally in system A are being replicated between system A and system B. In the first tenant being replicated, two of three namespaces are selected for replication. In the second tenant being replicated, one of two namespaces is selected for replication.
- Two tenants created locally in system B are being replicated between system A and system B. In the first tenant, two namespaces are selected for replication. In the second tenant, one of three namespaces is selected for replication.
Uses
The active/active replication topology supports a cloud storage model, where any type of client request can be serviced equally by either HCP system involved in the replication link. With this topology, if one system becomes unavailable (for example, either unexpectedly or for scheduled maintenance), the other system can still provide all the required functionality.
With an active/active replication topology, the processing load can be distributed between the two systems. This distribution can be accomplished in two ways:
- By having some applications direct requests to one system and other applications direct requests to the other system. Typically, the assignment of applications to systems is based on geographic location.
With this configuration, a single shared DNS can enable requests to be redirected automatically from one system to the other in case one of the systems becomes unavailable.
- By using a load balancer to divide requests between the two systems. For each client request, the decision as to which system to target can be based on several factors, such as the current load on each system and the geographical distance between the client and each system.
With this configuration, if one system becomes unavailable, the load balancer simply directs all requests to the other system.