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May 21st, 2025 03:52
Dell R7525 server PCIE split cannot recognize the device
My server is Dell R7525, installed with Ubuntu, rasier2 slot6 pcie4 X16 slot is split into 4 X4, this pcie interface is connected to a 4-slot nvme adapter card, and the 3rd and 4th slots are plugged with 2 nvme solid state drives (Samsung 990pro (gen4) and Western Digital SN750 (gen3)), both of which can be recognized;
However, if the 1st slot is plugged with 990PRO and the 2nd slot is plugged with SN750, SN750 can be recognized, but 990PRO cannot be recognized;
If the 1st slot is plugged with SN750 and the 2nd slot is plugged with 990PRO, 990PRO can be recognized, but SN750 cannot be recognized
slot6 X16 is definitely split into 4 X4, not the split settings
The SSDs are all good
Restarting does not solve the problem
The adapter card is also fine, the problem still exists after changing the adapter card
Reinstalled Ubuntu system, the problem still exists
Replaced rasier2, the problem still exists
The idrac does not have any fault alarm
What could be wrong? It looks like there are 4 split X4s, one is broken?
Dell-Martin S
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May 21st, 2025 09:03
Hi,
Here are some further Troubleshooting Steps:
* Prioritize BIOS/UEFI Update: This is the easiest and most impactful step if not already done.
* Clear CMOS/NVRAM: A clean slate for the BIOS.
* Run Dell Diagnostics: If available, run comprehensive diagnostics on the server to check the PCIe subsystem.
* Homogeneous Drive Testing: If the above don't work, this is the next crucial test.
Given the consistent failure of specific "logical" slots (1st and 2nd, even when the physical drive is moved), and the fact that the 3rd and 4th slots consistently work, it strongly suggests an issue with the specific PCIe lanes associated with the 1st and 2nd bifurcated slots, likely on the motherboard's PCIe controller or the traces leading to the riser. If all else fails, and especially if you've already tried a different riser, a motherboard replacement might be the ultimate solution, but exhaust all other avenues first.