Dell PowerVault MD3000 - Manual (Page 51)

About Your Host 51
I/O Data Path Protection
You can have multiple host-to-array connections for a host. Make sure to
select all of the connections to the array when configuring host access to the
storage array.
NOTICE: Refer to the Installation Guide for more information on cabling
configurations.
NOTE: For maximum redundancy, you must select all host connections to the array
when manually defining host topology. For example, a host might have two host
connections listed when manually configuring host access. For this host, you would
select the two host connections listed in the "Available hosts" section and add them
to the "Selected hosts" section using the Add button.
NOTE: For more information on configuring hosts see "About Your Host" on page 43.
If a component such as a RAID controller module or a cable fails, or an error
occurs on the data path to the preferred RAID controller module, virtual disk
ownership is moved to the alternate nonpreferred RAID controller module for
processing. This failure or error is called failover.
Multi-path drivers such as MPIO and MPP are installed on host systems that
access the storage array and provide I/O path failover. The multi-path driver
(MPIO in Windows and MPP in Linux) is used for failover. Automatic Virtual
Disk Transfer (AVT) is used specifically for single-port cluster failover. The
AVT feature mode is automatically selected by host type.
NOTE: You should have the multi-path driver installed on the hosts at all times,
even in a configuration where there is only one path to the storage system, such as
a single port cluster configuration.
During a failover, the virtual disk transfer is logged as a critical event, and an
alert notification is sent automatically if you have configured alert
destinations for the storage array.