Monday, March 17, 2014


Had a great question I wanted to share with you all (names omitted to protect the innocent).  The question was “When doing a motherboard swap or FC HBA swap, why do target WWPN’s not change?”

Answer: Basically WWPN’s are hard coded into the initiator ports but the WWPN’s for target ports are calculated based on the WWNN (see here) and retained statically by ONTAP.

To directly answer the question: “As long as the existing root volume is used in the head swap or upgrade, the same port-to-WWPN mapping applies. For example, port 0a on the replacement head has the same WWPN as the original head. If the new head has different adapter ports, the new ports are assigned new WWPNs.” 
Also interesting:

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