This is not really a recommended HBA, doesn't mean it won't work correctly, just that we usually recommend LSI since they are used for many users and the driver is usually solid, but not sure if the HBA is the problem:
Aug 13 10:44:36 FancherData kernel: hpsa 0000:01:00.0: handle_ioaccel_mode2_error: device is gone!
Aug 13 10:44:36 FancherData kernel: sd 7:0:6:0: [sdg] tag#851 UNKNOWN(0x2003) Result: hostbyte=0x01 driverbyte=0x00
first it was disk6 then all the other disks:
Aug 13 10:44:36 FancherData kernel: hpsa 0000:01:00.0: handle_ioaccel_mode2_error: device is gone!
Aug 13 10:44:36 FancherData kernel: sd 7:0:1:0: [sdb] tag#856 UNKNOWN(0x2003) Result: hostbyte=0x01 driverbyte=0x00
Aug 13 10:44:36 FancherData kernel: sd 7:0:1:0: [sdb] tag#856 CDB: opcode=0x88 88 00 00 00 00 03 6f da b4 c8 00 00 00 08 00 00
Aug 13 10:44:36 FancherData kernel: print_req_error: I/O error, dev sdb, sector 14761505992
Aug 13 10:44:36 FancherData kernel: md: disk2 read error, sector=14761505928
Aug 13 10:44:36 FancherData kernel: hpsa 0000:01:00.0: handle_ioaccel_mode2_error: device is gone!
Aug 13 10:44:36 FancherData kernel: sd 7:0:3:0: [sdd] tag#861 UNKNOWN(0x2003) Result: hostbyte=0x01 driverbyte=0x00
Aug 13 10:44:36 FancherData kernel: sd 7:0:3:0: [sdd] tag#861 CDB: opcode=0x88 88 00 00 00 00 03 6f da b4 c8 00 00 00 08 00 00
Aug 13 10:44:36 FancherData kernel: print_req_error: I/O error, dev sdd, sector 14761505992
Aug 13 10:44:36 FancherData kernel: md: disk1 read error, sector=14761505928
Aug 13 10:44:36 FancherData kernel: hpsa 0000:01:00.0: handle_ioaccel_mode2_error: device is gone!
Aug 13 10:44:36 FancherData kernel: sd 7:0:4:0: [sde] tag#867 UNKNOWN(0x2003) Result: hostbyte=0x01 driverbyte=0x00
Aug 13 10:44:36 FancherData kernel: sd 7:0:4:0: [sde] tag#867 CDB: opcode=0x88 88 00 00 00 00 03 6f da b4 c8 00 00 00 08 00 00
Aug 13 10:44:36 FancherData kernel: print_req_error: I/O error, dev sde, sector 14761505992
Aug 13 10:44:36 FancherData kernel: md: disk3 read error, sector=14761505928
Aug 13 10:44:36 FancherData kernel: hpsa 0000:01:00.0: handle_ioaccel_mode2_error: device is gone!
Aug 13 10:44:36 FancherData kernel: sd 7:0:5:0: [sdf] tag#868 UNKNOWN(0x2003) Result: hostbyte=0x01 driverbyte=0x00
Aug 13 10:44:36 FancherData kernel: sd 7:0:5:0: [sdf] tag#868 CDB: opcode=0x88 88 00 00 00 00 03 6f da b4 c8 00 00 00 08 00 00
Aug 13 10:44:36 FancherData kernel: print_req_error: I/O error, dev sdf, sector 14761505992
Aug 13 10:44:36 FancherData kernel: md: disk0 read error, sector=14761505928
Aug 13 10:44:36 FancherData kernel: hpsa 0000:01:00.0: handle_ioaccel_mode2_error: device is gone!
Aug 13 10:44:36 FancherData kernel: sd 7:0:7:0: [sdi] tag#869 UNKNOWN(0x2003) Result: hostbyte=0x01 driverbyte=0x00
Aug 13 10:44:36 FancherData kernel: sd 7:0:7:0: [sdi] tag#869 CDB: opcode=0x88 88 00 00 00 00 03 6f da b4 c8 00 00 00 08 00 00
Aug 13 10:44:36 FancherData kernel: print_req_error: I/O error, dev sdi, sector 14761505992
Aug 13 10:44:36 FancherData kernel: md: disk29 read error, sector=14761505928
Aug 13 10:44:36 FancherData kernel: hpsa 0000:01:00.0: handle_ioaccel_mode2_error: device is gone!
Aug 13 10:44:36 FancherData kernel: sd 7:0:8:0: [sdj] tag#870 UNKNOWN(0x2003) Result: hostbyte=0x01 driverbyte=0x00
Aug 13 10:44:36 FancherData kernel: sd 7:0:8:0: [sdj] tag#870 CDB: opcode=0x88 88 00 00 00 00 03 6f da b4 c8 00 00 00 08 00 00
Aug 13 10:44:36 FancherData kernel: print_req_error: I/O error, dev sdj, sector 14761505992
Aug 13 10:44:36 FancherData kernel: md: disk5 read error, sector=14761505928
Aug 13 10:44:36 FancherData kernel: md: recovery thread: multiple disk errors, sector=14761505928
Aug 13 10:44:36 FancherData kernel: sd 7:0:7:0: [sdi] tag#857 UNKNOWN(0x2003) Result: hostbyte=0x01 driverbyte=0x00
Note that when this happens Unraid disables as many devices as there are parity disks, which devoices get disabled is luck of the draw.
Now all disks dropping at the same time could be a connection problem, power problem or the HBA, but basically you need to start testing one thing at a time.