[dm-devel] [PATCH] multipath-tools: multipath should allow only path with valid size to get added in the map

[Hannes Reinecke]

On Fri, Nov 20, 2009 at 01:57:15PM -0800, Chandra Seetharaman wrote:
> Looks good to me except one comment below.
> 
> On Fri, 2009-11-20 at 20:38 +0530, Chauhan, Vijay wrote:
> > Hi,
> > 
> > If READ_CAPACITY fails during device discovery, sd device gets attached
> > with device size 0. Currently multipath discover these paths and adds
> > into the map. RDAC patch checker sends inquiry on each path to check
> > path status, which eventually marks this path as up. If this path is
> > from owning controller then mode select will be issued to switch the
> > pathgroup. But any I/O sent to this path(path with size 0) will eventually
> > fail in sd_prep_fn due to incorrect device size and resulting to ping pong
> > between pathgroups.  We should only allow valid paths to get added in the
> > map. Below patch checks two cases before adding paths; i.e.:
> > 	1) device size of path is not 0
> > 	2) there is no mismatch between mpp size and new path size.
> > 
> > 
Careful here. Some storage arrays (like the old HP MSA firmware) will report
a size of zero for the inactive path. So we must make sure to not kill support
for those.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		      zSeries & Storage
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