[dm-devel] NVMeoF multi-path setup

[Mike Snitzer]

On Thu, Jun 30 2016 at  6:52pm -0400,
Mike Snitzer <snitzer at redhat.com> wrote:

> Also, just so you're aware, I've staged bio-based dm-multipath support
> for the 4.8 merge window.  Please see either the 'for-next' or 'dm-4.8'
> branch in linux-dm.git:
> https://git.kernel.org/cgit/linux/kernel/git/device-mapper/linux-dm.git/log/?h=for-next
> https://git.kernel.org/cgit/linux/kernel/git/device-mapper/linux-dm.git/log/?h=dm-4.8
> 
> I'd welcome you testing if bio-based dm-multipath performs better for
> you than blk-mq request-based dm-multipath.  Both modes (using the 4.8
> staged code) can be easily selected on a per DM multipath device table
> by adding either: queue_mode=bio or queue_mode=mq
> 
> (made possible with this commit:
> https://git.kernel.org/cgit/linux/kernel/git/device-mapper/linux-dm.git/commit/?h=dm-4.8&id=e83068a5faafb8ca65d3b58bd1e1e3959ce1ddce
> )

Sorry, no = should be used. you need either:
"queue_mode bio" or "queue_mode mq"

Added to the features section of the "multipath" ctr input.
AFAIK, once the above commit lands upstream Ben will be adding some
multipath-tools code to make configuring queue_mode easy (but I think
multipath.conf may allow you to extend the features passed on a
per-device basis already.. but I'd have to look).