[dm-devel] Re: Is there a grand plan for FC failover?

[Patrick Mansfield]

On Wed, Jan 28, 2004 at 10:55:23PM +0000, Joe Thornber wrote:
> On Wed, Jan 28, 2004 at 12:47:56PM -0800, Patrick Mansfield wrote:
> > [cc-ing dm-devel]
> > If we end up passing all the scsi information up to dm, and it does the
> > same things that we already do in scsi (or in block), what is the point of
> > putting the code into a separate layer?
> 
> I don't know anything about the scsi layer, so I'm not sure exactly
> what the information is that you're after.  Is this information just
> used for path selction ?  If so a scsi specific path-selector could be
> written that plugs into the core multipath code.

Yes. Primarily whether or not we have a host (per-path) or device specific
failure.

The solution I have in mind would be non-scsi specific: pass up -errno
values, or special BLK_ERR_FOO values. Currently, blk always gives back a
-EIO on failure, and no even checks the result (as far as I've audited the
code).

-- Patrick Mansfield