NF5466M5: A Faulty SLOT19 Drive Prevented Detection of Other Drives

Symptom and source limitations

The NF5466M5 case reports that only 12 drives were detected and 26 others were not (24 at the front and two at the rear). The source also calls the configuration “36 drives” while listing 24 front plus 12+2 rear drives. These totals are inconsistent; confirm the actual configuration rather than using this note as a bay-layout specification.

Troubleshooting recorded in the case

1. Replaced the front drive backplane; the symptom remained.
2. Replaced the RAID controller; the symptom remained.
3. Removed the upper front backplane; the symptom remained.
4. The note says removal of a “lower rear backplane” restored detection of 12 front plus 12+2 rear drives. It then says that disconnecting power from the lower front backplane cleared the fault. The front/rear wording is inconsistent in the source.
5. Suspected inadequate motherboard power delivery and replaced the motherboard.
6. The symptom remained after motherboard replacement.
7. Swapped the upper and lower front backplanes; the symptom remained.
8. Removed the bottom 12 drives and powered the lower front backplane outside the chassis; the symptom disappeared.
9. Reinstalled the lower front backplane and inserted the drives one at a time.
10. Inserting the drive in SLOT19 reproduced the fault; removing that drive cleared it. This reading follows the source’s final resolution despite a typo in the preceding sentence.

Resolution

Replaced the SLOT19 drive. The case concluded that a single defective drive caused the detection failure.

The external-power step records what the field engineer did; it is not a general instruction to power a backplane using an unverified supply or wiring arrangement.