An error was encountered and the unit is now operating in degraded (non-redundant) mode. This is usually due to a drive failure or the physical removal of a drive from a redundant unit.
Check hardware connections and reseat the drive or drives. Rescan the controller from 3DM2 or CLI to see if the unit has been restored. If you are able to restore the unit before any data has been written to the unit, a rebuild will not be necessary. If the unit remains degraded, replace the missing or dead drives and initiate a rebuild.