[dm-devel] [PATCH v5 3/3] dm mpath: add CONFIG_DM_MULTIPATH_SG_IO - failover for SG_IO

[Christoph Hellwig]

On Thu, Jul 01, 2021 at 12:35:53PM +0200, Martin Wilck wrote:
> I respectfully disagree. Users of dm-multipath devices expect that IO
> succeeds as long as there's at least one healthy path. This is a
> fundamental property of multipath devices. Whether IO is sent
> "normally" or via SG_IO doesn't make a difference wrt this expectation.

If you have those (pretty reasonable) expections don't use SG_IO.
That is what the regular read/write path is for.  SG_IO gives you
raw access to the SCSI logic unit, and you get to keep the pieces
if anything goes wrong.