nvmetcli restore fails in add_subsystem

[Hannes Reinecke]

On 4/9/25 13:58, Anton Gavriliuk wrote:
> Hhmmm.....
> 
> The link - https://documentation.suse.com/sles/15-SP6/html/SLES-all/cha-nvmeof.html
> 
> is quite confused me,
> 
> 17.4.3 Marvell
> 
> FC-NVMe is supported on QLE269x and QLE27xx adapters. FC-NVMe support
> is enabled by default in the Marvell® QLogic® QLA2xxx Fibre Channel
> driver.
> 
> So if "the qla2xxx driver or/and the HBA firmware do not support the
> target mode anymore.", it is not clear, will NVMe/FC target work with
> QLE269x and QLE27xx adapters or not.
> 
It does not. The HBA model is irrelevant as the code to run nvme target
mode on QLogic HBAs is not present.

>> Though he was able to get the target mode running with a Emulex HBA (lpfc driver).
> 
> Long live Emulex!
> 
Kudos to James Smart; he was the main driver behind the NVMe-FC effort.

> P.S., I don't like FC, but I want to do some NVMe/FC vs TCP
> performance tests, so I must set up NVMe/FC for the tests.
> 
I am not sure how far you get with that. There is a differential
in transport speeds (10/25/50/100 for Ethernet, 16/32/64 for FC),
and the best you can hope is to reach line speed.
In my tests we reach line speed out of the box for 10GigE and
16G FC. I did some tests with 32G FC, but that was inconclusive
as it _heavily_ depended on the hardware setup (How many CPUs?
How many queues are exposed? Which backend did one use?).
And I do expect the picture is even worse for 100GigE.

But it'll be on my agenda to do some benchmarking here, too.

 From a practical side, FC is far more robust than Ethernet.
Thing is, traffic on FC is well managed, and one can expect
reliable performance characteristics throughout the lifetime
of the connection.
Ethernet, OTOH, is prone to outside influence as typically the
switches are used for all traffic (not just I/O), and hence packet
drops and performance drops are for more likely.

Which in the end will be far more important than raw speed.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke                  Kernel Storage Architect
hare at suse.de                                +49 911 74053 688
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