There are many causes for host unable to discover the storage over FCoE. Such as VLAN configuration on FCoE switch, improper zoning, driver issues etc. In this post, we will talk about VN2VN mode. What is VN2VN mode and how it makes a difference?
VN2VN mode:
Virtual N_port to VN_port connecting two FCoE adapters on Layer 2 lossless Ethernet network to discover and connect compatible FCoE devices to run storage traffic. Due to the limitation on the partially offloaded cards on ESXi host, we can choose only one mode, i.e. VN2VN or Fabric mode.
One of the reasons for not able to discover the storage over FCoE is miss-configured modes. For Example, Host is connected to the FCoE Switch, and the Host’s adapter is configured for VN2VN or vice versa.
How to verify the FCoE configuration :
- Verify FCoE adapter properties on ESXi host
# esxcli fcoe adapter list
vmhba33:
Source MAC: ec:b1:d7:9f:5c:e1
FCF MAC: c8:cb:b8:a5:b9:62
VNPort MAC: 0e:fc:01:0a:15:10
Physical NIC: vmnic8
User Priority: 3
VLAN id: 0
VN2VN Mode Enabled: trueAbove output shows Physical NIC used, VLAN and FCoE Mode. The output clearly shows that VN2VN mode is enabled. FCoE adapter does not have any VLAN discovered.
If FCoE switch is connected to the host, then this configuration is wrong. Which is the cause for unable to discover storage or sometimes storage gets discovered manually but after reboot, auto-discover dose not work.
To correct the configuration follow :
- Disable VN2VN mode
# esxcfg-fcoe -X vmnic8Note: This change needs a reboot to take effect.
- Once the host is rebooted, discover the storage for the host.
# esxcfg-fcoe -d vmnic8The correct output will look like :
# esxcli fcoe adapter list
vmhba33:
Source MAC: ec:b1:d7:9f:5c:e1
FCF MAC: c8:cb:b8:a5:b9:62
VNPort MAC: 0e:fc:01:0a:15:10
Physical NIC: vmnic8
User Priority: 3
VLAN id: 1001
VN2VN Mode Enabled: falseOnce the Correct VLAN is discovered, HBA will be able to login to the Fabric. Which will discover the storage.