Solution if Fibre Channel links are intermittently disconnected

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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.

Other related questions:
Solution when abnormal Fibre Channel connections occur
Symptom 1: On the ISM GUI, a message is displayed indicating that the initiator is not connected or the port is offline. Possible cause: The networking is incorrect. The optical cable or optical module is faulty. Recommended action: Check whether the optical module, optical cable, and networking are correct. Check whether the optical module and optical cable are inserted properly. Check whether abnormal port information is displayed. Check whether the logical connection is faulty. Symptom 2: The networking and hardware is normal. However, on the ISM GUI, a message is still displayed indicating that the initiator is not connected and the port is offline. Possible causes: Configuration problem: The rate, port mode, and topology mode do not match. Host problem: The HBA card drive does not match and the HBA card is faulty. Recommended action: Check whether the rate, port mode, and topology mode are correct. View the message log and check whether there are intermittent disconnection.

Problem and solution when adding a Fibre Channel link fails in an OceanStor V3 storage system but the log indicates that adding an iSCSI link fails
Cause: The alarm baseline document is updated but the CLI is not updated accordingly. Solution: 1. View the information about alarm 0x200F00E00024 in OceanStor DeviceManager. 2. Upgrade the storage system to the latest version. 3. Contact Huawei after-sales service personnel.

Whether the port bonding is supported for Fibre Channel host ports on OceanStor T Series storage systems
OceanStor V100R005 T series storage systems do not support the bonding of Fibre Channel host ports.

Rule of identifying initiators in a Fibre Channel network
You can follow the following rules to identify initiators in a Fibre Channel network: 1. Issue Description In a network where an application server is connected to a storage system through a Fibre Channel switch, after an initiator is added to the host, is the initiator identified by the WWN of the Fibre Channel switch or the WWN of the Fibre Channel HBA on the application server? 2. Solution No matter whether the Fibre Channel switch is installed or not, the Fibre Channel initiator is identified by the WWN of the Fibre Channel HBA of the application server.

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