WWPN HBA Swap

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.” 

https://library.netapp.com/ecmdocs/ECMP1136382/html/html/210-05627/GUID-0F9B2EC3-845C-4D66-BCE8-CC252E927EC7.html

Also interesting:

https://kb.netapp.com/support/index?page=content&id=1013497

Ports

Quick hits on ports because it keeps being brought up:

• There are no 4 port 10GbE cards.
• Only onboard ports can be changed from initiator to target or visa versa.
• WWPN's are hard coded into the cards and onboard INITIATOR ports.
• You can change WWPN's on target ports.

NetApp Training Brain Dump: Quick Hits

Here are some important facts to note that don't really belong in my other posts.  I'll keep this updated over the next couple weeks.

Quick Hits:

1. You can suspend a specific protocol (e.g., turn off CIFS access).
2. 500A098 is NetApp's base WWPN string.
3. ~80% of NetApp's hardware support calls are the hot swappable units (Fan, PSU, Drive).
4. There are about 40,000 FAS systems in the US, 150,000 in the world (4/24/11).
5. Don't use HyperTerminal to access a FAS system console.  PuTTY is your friend.
6. Give SAS/SATA/FC their own shelves and loops.  Don't mix and match.
7. The FAS3140 doesn't have the 2 minute PSU countdown to a system halt, but best practice is still 2 minute replacement time.
8. FAS2000 series internal disks are unusual and specific.
9. FC disks are up to 750GB now (4/24/11)
10. ONTAP data blocks are minimum 4k.