The building block approach can be used in an N+1 architecture in which an idle server stands by to replace any one of N servers that may fail. The "+1" server could also be used to run as an extra, hot standby server running IIS to take some of the workload from the other servers.

In an active/active architecture an existing server can take on the additional workload of a failed server. An active/active solution can be implemented if servers have spare capacity to handle extra work. After failover the net performance may drop, depending on the amount of spare capacity. Thought must be given to this during the design stage.

See About Enterprise Vault building blocks

See About Enterprise Vault services in building blocks configurations