I should clarify that in this case the storage array was an old HP XP-512 that we are migrating away from.  But it made us realize that we didn't have any mechanism in place to alert us when a host (on this array or on NTAP) loses one of its paths. 
 
The latest revs of HP's client-side MPIO application for the XP (it's called auto path and I doubt very strongly that it would work with an NTAP array) does have its own SNMP MIB and even an e-mail alerting feature.  I was hoping that the NTAP MPIO DSM might have something similar.
 
To answer your question, we do believe the head is to blame because we've swapped out every other component - HBAs, fibre cables, Brocade switches.  And we don't think it's a software issue because the HBA that connects to the bad path has no comm even when configuring the boot BIOS during the POST.  However, the diagnostics dumps that the backline support engineers generated on the head show everything as fine, so this is one of those fairly subtle issues where the client can't communicate over one path but every component is reporting a status of OK.  Hence the interest in a client-side utility.
 
I did find that I could run c:\Program Files\NetApp\mpio\dsmcli path list to generate a (barely) human-readable list of paths, but it would take some effort to automate and I figured if the DSM is already gathering this data then it may have another interface for retrieving it.

From: Webster, Stetson [mailto:Stetson.Webster@netapp.com]
Sent: Tuesday, April 08, 2008 10:08 AM
To: Jon Hill; toasters@mathworks.com
Subject: RE: MPIO and path failure

Paths are merely a route **TO** the filer, but rather something **ON** the filer. 
 
Therefore, that's an environmental issue external to the filer (rather than something actually on the filer).  So you would need to investigate this with your switch vendor, etc.
 
Do you perhaps have some indication that something on the filer failed and caused this?
 

Stetson M. Webster
Onsite Professional Services Engineer
PS - North Amer. - East

NetApp
919.250.0052 Mobile
Stetson.Webster@netapp.com
www.netapp.com
 

From: Jon Hill [mailto:JHill@jennison.com]
Sent: Tuesday, April 08, 2008 8:06 AM
To: toasters@mathworks.com
Subject: MPIO and path failure

We had an incident the other day where we lost one of our two paths to storage.  We noticed the path failure quite by accident, and some time after it actually happened. 

Does anyone know whether there's a way that the NTAP fibre DSM can be configured to generate an alert (by SNMP or e-mail) whenever a path fails?