[dm-devel] [PATCH 4/9] multipath-tools: add NetApp E-Series NVMe to hardware table

[Schremmer, Steven]

Martin W,

> Steve,
> 
> On Wed, 2022-05-18 at 20:24 +0000, Schremmer, Steven wrote:
> >
> > Nak. NetApp E-Series only supports these settings in certain
> > configurations, and we prefer to handle it via our installation
> > documentation.
> >
> 
> I don't follow. What harm is done to Netapp if these settings are
> included? People can still follow your documentation, the end result
> will be the same... no?
> 
> AFAICS, the only setting above that would only be supported in certain
> configurations is PRIO_ANA, without which GROUP_BY_PRIO doesn't make
> much sense. If the array is configured not to support ANA, this
> configuration would lead to error messages and PRIO_UNDEF for all
> paths, and thus "imply" multibus topology. Not beautiful, but also no
> big harm done, IMO.
> 
> If it's that you're concerned about, please provide the set of defaults
> you prefer for E-Series, or explictly state that you prefer to run with
> the generic NVMe defaults (const prio, failover policy).
> 
> In general, if vendor-recommended settings are strongly dependent on
> storage configuration, host-side software defaults must try to match
> the storage array's defaults. We shoud do this for E-Series, too. If
> ANA needs to be explicitly enabled on the array by the admin, we
> shouldn't enable it by default; but otherwise, we should.
> 
> Martin

NVMe-attached E-Series is moving towards only using the native NVMe
multipathing in the kernel rather than DM-MP with NVMe. At some point
we will stop interoperability testing with NVMe DM-MP and not certify new
solutions with it.

The set of defaults listed for NVMe E-Series are the correct ones, but I'm not sure
they should be included if we aren't going to continue to test the interoperability
of NVMe-attached E-Series and DM-MP.

Thanks,
Steve