On Mon, Sep 18, 2017 at 04:14:53PM -0700, Christoph Hellwig wrote:

This patch adds initial multipath support to the nvme driver.  For each
namespace we create a new block device node, which can be used to access
that namespace through any of the controllers that refer to it.

Currently we will always send I/O to the first available path, this will
be changed once the NVMe Asynchronous Namespace Access (ANA) TP is
ratified and implemented, at which point we will look at the ANA state
for each namespace.  Another possibility that was prototyped is to
use the path that is closes to the submitting NUMA code, which will be
mostly interesting for PCI, but might also be useful for RDMA or FC
transports in the future.  There is not plan to implement round robin

                                    no ^

or I/O service time path selectors, as those are not scalable with
the performance rates provided by NVMe.

The multipath device will go away once all paths to it disappear,
any delay to keep it alive needs to be implemented at the controller
level.

Sorry for the typo only mail, I'll be going around a real review soon but I
wanted to test the patchset in my nvme-rdma setup and just hit a panic in
ib_core with your branched merged into -rc1.

Byte,
	Johannes

-- 
Johannes Thumshirn                                          Storage
jthumshirn@suse.de                                +49 911 74053 689
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