Dell Storage Center SCv2000 and SCv2020 Storage System Deployment Guide

Types of Redundancy for Front-End Connections

Front-end redundancy is achieved by eliminating single points of failure that could cause a server to lose connectivity to the Storage Center.

Depending on how the Storage Center is cabled and configured, the following types of redundancy are available.

Table 1. Redundancy and Failover Behavior
Redundancy	Failover Behavior
Asymmetric Logical Unit Access (ALUA)	If a storage controller becomes unavailable, all the standby paths on the other storage controller become active.
Port redundancy	If a single port becomes unavailable, the port can move to another available port in the same fault domain.
Storage controller redundancy	If a storage controller becomes unavailable, the ports on the offline storage controller can move to the available storage controller .
Path redundancy	When multiple paths are available from a server to a storage system, a server configured for multipath I/O (MPIO) can use multiple paths for I/O. If a path becomes unavailable, the server continues to use the remaining available paths.