64 Installing and Configuring HardwareSetting up Redundant Path Support on thePERC H800 AdapterThe PERC H800 adapter can detect and use redundant paths to diskscontained in enclosures. With redundant paths to the same device, if onepath fails, another path can be used to communicate between the controllerand the device. For more information about redundant paths, see "RedundantPath With Load Balancing Support" on page 35.To set up a configuration with redundant paths, both ports on a controllermust be cabled to the In ports of a single enclosure.To add multiple enclosures, both Out ports of the first enclosure must becabled to the In ports of the next enclosure.If the connection between an Out port on the controller and an In port on anenclosure fails, an alternate path exists through the second Out port on thecontroller and the second In port on the enclosure. For more information,see Figure 4-18 to Figure 4-21.NOTE: The PERC H800 adapter supports redundant paths when used withDell PowerVault MD1200 and Dell PowerVault MD1220 disk storage enclosures.Perform the following steps to configure the hardware to utilize redundantpaths on the PERC H800 adapter:1 Set up an enclosure on the PERC H800 adapter.2 Connect two SAS cables from the Out ports on your PERC H800 adapterto the In ports of the external enclosure. For more information,see Figure 4-18.NOTE: For information on Unified Mode, see the enclosure documentationthat was shipped with the enclosure.3 To add multiple enclosures, cable both Out ports of the first enclosure toboth In ports of the next enclosure.After you set up the hardware, the controller detects the redundant paths andautomatically utilizes them to balance the I/O load.
