There's a problem with disk3:
Feb 26 15:06:30 Tower kernel: mpt2sas_cm0: log_info(0x31110d00): originator(PL), code(0x11), sub_code(0x0d00)
Feb 26 15:06:30 Tower kernel: sd 1:0:6:0: [sdl] tag#1698 UNKNOWN(0x2003) Result: hostbyte=0x00 driverbyte=0x08
Feb 26 15:06:30 Tower kernel: sd 1:0:6:0: [sdl] tag#1698 Sense Key : 0x2 [current]
Feb 26 15:06:30 Tower kernel: sd 1:0:6:0: [sdl] tag#1698 ASC=0x4 ASCQ=0x0
Feb 26 15:06:30 Tower kernel: sd 1:0:6:0: [sdl] tag#1698 CDB: opcode=0x88 88 00 00 00 00 00 ae a8 a8 58 00 00 01 08 00 00
Feb 26 15:06:30 Tower kernel: print_req_error: I/O error, dev sdl, sector 2930288728
Feb 26 15:06:30 Tower kernel: md: disk3 read error, sector=2930288664
Feb 26 15:06:30 Tower kernel: md: disk3 read error, sector=2930288672
Feb 26 15:06:30 Tower kernel: md: disk3 read error, sector=2930288680
Feb 26 15:06:30 Tower kernel: md: disk3 read error, sector=2930288688
Feb 26 15:06:30 Tower kernel: md: disk3 read error, sector=2930288696
Feb 26 15:06:30 Tower kernel: md: disk3 read error, sector=2930288704
Start by replacing/swapping cables.