NVMe over Fibre Channel support and certification status.

Solution Verified - Updated -

Environment

  • Red Hat Enterprise Linux 7.5
  • Emulex Light Pulse Fibre Channel HBA using the lpfc driver and capable of NVMe over Fibre Channel

Issue

  • NVMe over Fibre Channel support and certification status.
  • Is NVMe over Fibre Channel supported in RHEL?
  • Why does my system have a tainted kernel when using the lpfc driver in 7.5?
  • What are the nvme_fc and nvmet_fc modules and why do they taint the kernel?

Resolution

NVMe over Fibre Channel is a Technology Preview in Red Hat Enterprise Linux 7.5

Certain Fibre Channel HBAs are capable of NVMe over fibre channel in 7.5. However, since it is a Tech Preview feature, it is not tested as part of Red Hat's Hardware Certification program.

If this article is linked to a system in the Certification Catalog, the NVMe over Fibre Channel functionality was not tested with the optional Fibre Channel HBAs in the system, and NVMe over Fibre Channel with these devices and the Red Hat supplied inbox driver should not be used in a production environment.

Root Cause

The Red Hat supplied inbox lpfc driver enables NVMe over Fibre Channel, as such it causes the nvme_fc and nvmet_fc modules to automatically load as dependencies. These modules are marked Tech Preview, and as such, they taint the kernel. It is not currently possible to blacklist these modules and still have the device fully functional even for non-NVMe storage. As long as customers do no use the NVMe over Fibre Channel feature of these devices, it will not affect the supportability of the lpfc driver and associated devices.

If you have any further questions regarding the supportability status of the Fibre Channel HBA or the NVMe over Fibre Channel capabilities of this system, please contact the hardware vendor.

Diagnostic Steps

To confirm you are not enabling NVME over FC with the lpfc driver ensure that /sys/module/lpfc/parameters/lpfc_enable_fc4_type is set to 1. Any other value indicates that NVMEoFC is enabled and the rules governing Technology Preview features apply.

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