A RAID (redundant array of independent disks) hot spare (RHS) system and method that permits a daisy-chain of interconnected pass-thru disk drive controllers (PTDDCs) each connected to a SATA local disk drive (LDD) storage element (DSE) to support a hot spare disk (HSD) such that a failing disk drive (FDD) in the RAID array can be immediately replaced by a HSD within the PTDDC daisy-chain without operator intervention is disclosed. The PTDDCs within the daisy-chain are configured in RAID fashion to support mirroring of one or more drives in the PTDDC daisy-chain. The PTDDCs monitor functional status of LDDs attached to each PTDDC. FDD failure triggers activation of a HSD in the PTDDC daisy-chain and automatic mirror copying along the PTDDC daisy-chain of RAID data from a master disk drive (MDD) mirrored to the LDD. FDD-PTDDC and HSD-PTDDC LBA mapping registers are updated after mirror copying completes.