Dell PowerVault 775N (Rackmount NAS Appliance) - Manual (Page 15)

Cluster Service.
Failover Policies
When implementing a failover policy, configure failback if the cluster node lacks the resources (such as memory or processing
power) to support one or more cluster node failures.
Windows Storage Server 2003, Enterprise Edition Cluster
Configurations
NAS cluster configurations running Windows Storage Server 2003, Enterprise Edition provides the following failover policies:
N + I failover
Failover pair
Multiway failover
Failover ring
N + I Failover
N + I failover (where N = the number of active nodes and I = the number of inactive [or passive] nodes) is an active/passive
failover policy where dedicated, passive cluster node(s) provide backup for the active cluster node(s). This failover solution
provides the best solution for critical applications that require dedicated server resources. However, the backup cluster nodes
add a higher cost of ownership to the cluster because they remain idle and do not provide the cluster with additional network
resources.
Figure 1-3 shows an example of a 6 + 2 (N + I) failover configuration with six active nodes and two passive nodes. Table 1-7
provides an N + I failover configuration matrix for Figure 1-3 .
Figure 1-3. Example of an N+I Failover Configuration for an Eight-Node Cluster
.