The problem is with an internal disk unit backplane. Use the following table to determine the part number for the field replaceable unit (FRU):
| CCIN or FFC | Type and model | Part number | Description | Location code |
| 199 | 8204-E8A | 10N9532 | Disk unit backplane | Un-P2 |
| 199 | 8204-E8A | 10N9664 | Disk unit backplane (with SAS expander) | Un-P2 |
| 199 | 9117-MMA | 03N4801 | Disk unit backplane | Un-P3 |