This post will cover the specifics about NPIV technology when using Live Partition Mobility.
NPIV: N_Port ID Virtualization.
It’s a Fibre Channel hardware feature. Multiple Fibre Channel node port IDs can share a single physical N_Port.
Each client partition has dedicated wwpns.
Disk drivers are installed at lpar level.
Load balancing available at lpar level.
Easiest virtualization solution for lan free backup.
Most popular disk virtualization technology on Power systems.
The disk driver is installed at partition level.
Disk paths load balancing is performed at partition level.
Most common setup is 4 paths. It allows to access each fabric from each VIOS.
active and inactive wwpns
When an active LPM operation is performed, the fibre channel adapter will use the inactive wwpn on the destination system. It will keep using it after the operation.
Zoning by WWPN is recommended. See Brocade reference documentation :
When using lscfg command, you will only see the first wwpn on the virtual fibre channel adapter.
# lscfg -vl fcs0 fcs0 U8286.42A.06B7D12-V10-C4-T1 Virtual Fibre Channel Client Adapter Network Address.............C0507607A2550166 ROS Level and ID............ Device Specific.(Z0)........ Device Specific.(Z1)........ Device Specific.(Z2)........ Device Specific.(Z3)........ Device Specific.(Z4)........ Device Specific.(Z5)........ Device Specific.(Z6)........ Device Specific.(Z7)........ Device Specific.(Z8)........C0507607A2550166 Device Specific.(Z9)........ Hardware Location Code......U8286.42A.06B7D12-V10-C4-T1
Here it’s C0507607A2550166.
To see what is the current active wwpn, you need to use fcstat command:
# fcstat fcs0 FIBRE CHANNEL STATISTICS REPORT: fcs0 Device Type: FC Adapter (adapter/vdevice/IBM,vfc-client) Serial Number: UNKNOWN Option ROM Version: UNKNOWN ZA: UNKNOWN World Wide Node Name: 0xC0507607A2550167 World Wide Port Name: 0xC0507607A2550167 FC-4 TYPES: Supported: 0x0000010000000000000000000000000000000000000000000000000000000000 Active: 0x0000010000000000000000000000000000000000000000000000000000000000 Class of Service: 3 Port Speed (supported): UNKNOWN Port Speed (running): 8 GBIT Port FC ID: 0x01086F
Here an active LPM operation occured, so it’s C0507607A2550167.
valid zoning and masking configuration
To perform LPM correctly, both active and inactive wwpns needs to be zoned and masked to the appropriate storage.
2 solutions are available:
one host defined at storage level with all wwpns
2 hosts defined at storage level: one with active wwpns, one with inactive wwpns.
If done properly, both solutions are valid.
Defining two hosts at storage level works but if the configuration is not identical, the system can be missing disks after an LPM move.
It happens when:
disks are missing in LPM host masking
disks doesn’t have the same scsi id in both host masking.
Recommendation: define only one host at storage level with all wwpns or use san disks level validation(available with vios 220.127.116.11 and above).
SAN disk level validation
Before VIOS 2.2.4(Dec 2015), LPM validation was only validating if the inactive wwpn was able to connect on the same storage port than the active wwpn on each virtual fibre channel adapter.
If host mapping was not exactly the same for the inactive wwpn, problems would arise.
If it’s not possible to ensure the zoning and mapping recommendations are applied, use disk level validation. The validation will take more time but will ensure all disks are visible on the target system.
It need to be enabled on all source vios :
chdev -dev vioslpm0 -attr src_lun_val=on