Re: [PATCH v6 00/16] nvmet: add target passthru commands support

Logan Gunthorpe
2019-07-29T16:17:30Z

On 2019-07-29 10:15 a.m., Sagi Grimberg wrote:
>
>>> This is different from multipath on say a multi-controller PCI device
>>> and trying to expose both those controllers through passthru. this is
>>> where the problems we are discussing come up.
>>
>> I *think* there is some confusion. I *think* Sagi is talking about network multi-path (i.e. the ability for the host to connect to a controller on the target via two different network paths that fail-over as needed). I *think* Logan is talking about multi-port PCIe NVMe devices that allow namespaces to be accessed via more than one controller over PCIe (dual-port NVMe SSDs being the most obvious example of this today).
>
> Yes, I was referring to fabrics multipathing which is somewhat
> orthogonal to the backend pci multipathing (unless I'm missing
> something).

Yes, so if we focus on the fabrics multipathing, the only issue I see is
that only one controller can be connected to a passthru target (I
believe this was at your request) so two paths simply cannot exist to
begin with. I can easily remove that restriction.

Logan