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MPIO is loosing paths?!?!

Hi,

 

we are currently facing a strange problem. We shifted to a new Fas8040 MetroCluster in 7-Mode.

Most of our systems are running virtualized on Microsoft HyperV in redundant fibre-channel environment (2 independent fabrics).

On our Windows Server 2012 R2 HyperV-Hosts we have the Data Ontap DSM 4.1 installed. The igroups have ALUA enabled.

 

The MPIO usually shows 4 paths, where 2 paths are "unoptimezed" and "disabled". From time to time ... I promise without any changes from our side and without any FC-Switch / Port Problems one or two physical HyperV hosts loose their optimized paths to the LUN and therefore take the vtic path.

 

What we have to do to change this behavior is quite simple ... Open device manager, right click, recsan for new hardware and ... woohooo ... all 4 paths are available again and traffic runs over the "good" paths again.

Any ideas what's going on???

 

What is the NetApp DSM "Enable Path Verify" Option for? It's disabled by default. Could this solve my problems?