1. A method for distributing input/output (IO) load in a Redundant Array of Independent Disks (RAID) storage system, the RAID storage system including a plurality of RAID volumes and a plurality of processors, the method comprising: determining whether the RAID storage system is operating in a write-through mode or a write-back mode; distributing the IO load to a particular processor selected among the plurality of processors when the RAID storage system is operating in the write-through mode, the particular processor being selected based on a number of available resources associated with the particular processor; and distributing the IO load among the plurality of processors when the RAID storage system is operating in the write-back mode, the distribution being determined based on: an index of a data stripe, and a number of processors in the plurality of processors.