To ensure that all servers are behind SAN and that cluster failover/failback is implemented, you must deploy 2n servers, where n is the number of iFolder servers the organization is planning to deploy in a multi-server environment. In this case, all the servers share the same storage array, with different partitions enabling the cluster to be effective. This means that every iFolder server has a backup node to support failover and failback and to provide high availability.
If hardware is a constraint, Apache virtual hosts can be leveraged, so that during a failover, the slave runs along with another slave in virtual host mode behind Apache. The only drawback is performance, because the Apache server must service twice the server load and number of user requests, which is not recommended unless the deployment has comparatively few user requests.