Solution if Fibre Channel links are intermittently disconnected

You can refer to the following case if Fibre Channel links are intermittently disconnected:
1. Issue Description
What can I do if Fibre Channel links are intermittently disconnected?
2. Solution
When the connection status of Fibre Channel links changes, you can view much information about connection between the storage system and host (or the storage system and switch) based on logs. Then you can check whether there are exceptions such as intermittent disconnection and whether the disconnection is caused by hosts or the storage system. If the disconnection is caused by hosts, check the links between the hosts and switch. If the disconnection is caused by the storage system, check the links between the storage system and switch. The following shows how the connections among the storage system, hosts, and switch are set up:
a. Setting up connection between the storage system and hosts
Note:
The PLOGI command is used to set up connection at the FC2 layer while the PRLI command is used to set up connection to the FC4 layer. After the storage system is connected to host 0x00010b00 at the FC4 layer, a drive reports the linkup event of the port to the upper layer.
b. Setting up connection between the storage system and switch
Note:
The commands FLOGI, PLOGI, RFT_ID, RFT_ID, RFF_ID, and SCR, are used to register the storage system on the switch. 0x000000d4 is PortID of the storage system while 0x22fffffe is PortID of the switch. After registered on the switch, the storage system can set up connection to the hosts.
c. The storage system reports the linkup event.
Note:
A linkup event is reported after the connections between the storage system and hosts/switch are set up.
d. The storage system reports the linkdown event.
Note:
An information TGT_LinkDown is displayed when the storage system is disconnected to the hosts or switch.
e. Fibre Channel network nodes change.
When the connection status of some nodes in a switch networking changes, the switch sends a registered state change notification (RSCN) to other nodes in the same domain. If the storage system receives RSCN, some hosts or storage systems are disconnected to the switch, or some new nodes are connected to the switch.
Note:
When the connection status of node 0x000101d4 changes, the switch sends RSCN to the storage system. In addition, the storage system sends GPN_ID to the switch to check whether node 0x000101d4 exists. If the storage system receives CT_RJT, node 0x000101d4 does not exist. Delete resources that connect to the node.

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