Re: [PATCH 1/2] nvme: check duplicate unique identifiers in order

Martin K. Petersen
2025-09-16T19:04:49Z

John,

>> The issue is pervasive enough that OCP has a defined EUI64 workaround
>> in their SSD spec.

[...]

> https://www.opencompute.org/documents/datacenter-nvme-ssd-specification-v2-6-2-pdf
>
> Is this the specification you are referring to?
>
> NVMe-CFG-7

> The single default namespace (see SECTOR-3) shall have a unique
> non-zero value in the EUI64 (Extended Unique Identifier) field in the
> Identify Namespace data structure. For each namespace that is created
> other than the initial namespace configured in the factory, the device
> shall clear the EUI64 field in the Identify Namespace data structure
> to 0h.

Correct.

I suspect there are a bazillion deployed drives which suffer from the
non-unique identifier problem. And thus the path of least resistance
appears to be to avoid reporting EUI64 for subsequent namespaces after a
firmware update. At least that keeps the existing EUI64 stable for the
common case where only a single namespace is provisioned.

--
Martin K. Petersen