556 A duplicate WWNN has been detected.

Explanation

The node detected another device that has the same Worldwide Node Name (WWNN) on the Fibre Channel network. A WWNN is 16 hexadecimal digits long. The last 5 digits of the WWNN are given in the additional data of the error. For more information, see "Service assistant interface." The Fibre Channel ports of the node are disabled to prevent disruption of the Fibre Channel network. One or both nodes with the same WWNN can show the error. Because of the way WWNNs are allocated, a device with a duplicate WWNN is normally another node.

User response

On systems other than IBM® SAN Volume Controller, complete the following steps:
  1. Find the node with the same WWNN as the node that is reporting the error. The WWNN for a node can be found from the node Vital Product Data (VPD) or from the node details shown by the service assistant. The node with the duplicate WWNN does not need to be part of the same cluster as the node that is reporting the error; it can be remote from the node that is reporting the error on a part of the fabric that is connected through an inter-switch link. The two nodes within a control enclosure must have different WWNNs. The WWNN of the node is stored within the enclosure chassis, so the duplication is most likely caused by the replacement of a control enclosure chassis.
  2. If a node with a duplicate WWNN is found, determine whether it, or the node that is reporting the error, has the incorrect WWNN. Generally, it is the node that had its enclosure chassis recently replaced or had its WWNN changed incorrectly. Also, consider how the SAN is zoned when you make your decision.
  3. Determine the correct WWNN for the node with the incorrect WWNN. If the enclosure chassis was replaced as part of a service action, the WWNN for the node was typically written down. If the correct WWNN cannot be determined, contact your support center for assistance.
  4. Use the service assistant to modify the incorrect WWNN. If it is the node that is showing the error that must be modified, this modification can safely be done immediately. If it is an active node that must be modified, use caution because the node restarts when the WWNN is changed. If this node is the only operational node in an enclosure, access to the volumes that it is managing is lost. Ensure that the host systems are in the correct state before you change the WWNN.
  5. If the node that is showing the error had the correct WWNN, it can be restarted, by using the service assistant, after the node with the duplicate WWNN is updated.
  6. If you are unable to find a node with the same WWNN as the node that is showing the error, use the SAN monitoring tools to determine whether another device is on the SAN with the same WWNN. This device must not be using a WWNN assigned to a system, so follow the service procedures for the device to change its WWNN. After the duplicate is removed, restart the node.
On IBM SAN Volume Controller, follow troubleshooting procedures to configure the WWNN of the node:
  1. Find the cluster node with the same WWNN as the node that is reporting the error. The WWNN for a cluster node can be found from the node Vital Product Data (VPD) or from the node details shown by the service assistant. The node with the duplicate WWNN does need not to be part of the same cluster as the node that is reporting the error; it can be remote from the node that is reporting the error on a part of the fabric that is connected through an inter-switch link.
  2. If a cluster node with a duplicate WWNN is found, determine whether it, or the node that is reporting the error, has the incorrect WWNN. Also, consider how the SAN is zoned when you make your decision.
  3. Determine the correct WWNN for the node with the incorrect WWNN. If the correct WWNN cannot be determined, contact your support representative for assistance.
  4. Use the service assistant to modify the incorrect WWNN. If it is the node that is showing the error that must be modified, this modification can safely be done immediately. If it is an active node that must be modified, use caution because the node restarts when the WWNN is changed. If this node is the only operational node in an I/O group, access to the volumes that it is managing is lost. Ensure that the host systems are in the correct state before you change the WWNN.
  5. If the node that is showing the error had the correct WWNN, it can be restarted, by using the front panel power control button after the node with the duplicate WWNN is updated.
  6. If you are unable to find a cluster node with the same WWNN as the node that is showing the error, use the SAN monitoring tools to determine whether if another device is on the SAN with the same WWNN. This device must not be using a WWNN assigned to a cluster, so follow the service procedures for the device to change its WWNN. After the duplicate is removed, restart the node.