Dell PowerEdge RAID Controller 10 User’s Guide PERC H345, H740P, H745, and H840 Series Controllers

The PERC H840 adapter can detect and use redundant paths to disks contained in enclosures. This provides the ability to connect two SAS cables between a controller and an enclosure for path redundancy. The controller can tolerate the failure of a cable or enclosure management module (EMM) by utilizing the remaining path. When redundant paths exist, the controller automatically balances I/O loads through both paths to each disk. Load balancing increases throughput to virtual disks in storage enclosures and is automatically turned on when redundant paths are detected. To set up your hardware to support redundant paths, see Setting up redundant path support on the PERC H840 adapter.