26.2. DM Multipath

DM Multipath is a feature that allows you to configure multiple I/O paths between server nodes and storage arrays into a single device. These I/O paths are physical SAN connections that can include separate cables, switches, and controllers. Multipathing aggregates the I/O paths, creating a new device that consists of the aggregated paths.
DM Multipath are used primarily for the following reasons:
Redundancy
DM Multipath can provide failover in an active/passive configuration. In an active/passive configuration, only half the paths are used at any time for I/O. If any element of an I/O path fails, DM Multipath switches to an alternate path.
Improved Performance
DM Multipath can be configured in active/active mode, where I/O is spread over the paths in a round-robin fashion. In some configurations, DM Multipath can detect loading on the I/O paths and dynamically rebalance the load.
For more information, see the Red Hat DM Multipath guide.