Technical information

June 2012 Dell EqualLogic Configuration Guide v13.2 11
2.3.7 Vertical Port Failover behavior in PS4100/PS6100 Controllers
In PS Series controllers prior to PS4100/6100 families, a link failure or a switch failure was not
recognized as a failure mode by the controller. Thus a failure of a link or an entire switch would
reduce bandwidth available from the array. Referring to Figure 4 or Figure 5, assume that CM0 is the
active controller. In vertical port failover, if CM0 senses a link drop on the local ETH0 port connection
path, it will automatically begin using the ETH0 port on the backup controller (CM1). Vertical port
failover is bi-directional. If CM1 is the active controller then vertical port failover will occur from CM1
ports to CM0 ports if necessary.
Figure 4 PS4100 Vertical Port Failover
Figure 5 PS6100 Vertical Port Failover
With PS4100/PS6100 family controllers, vertical port failover can ensure continuous full bandwidth is
available from the array even if you have a link or switch failure. This is accomplished by combining
corresponding physical ports in each controller (vertical pairs) into a single logical port from the point
of view of the active controller. In a fully redundant SAN configuration, you must configure the
connections as shown in Figure 19 and Figure 20.