OceanStor 5600 V3 It is unable to find LUN mapped on AIX host which connected with the storage through the FC optical fiber switch

Publication Date:  2015-12-15 Views:  209 Downloads:  1
Issue Description

AIX host establishes a normal connection with 5600 V3 through FC optic fiber switch. It doesnt automatically discovery FC initiator in storage, so customer adds the initiator and maps lun manually. But it cant discover the LUN mapping on the host after running the command to scan LUN.

Alarm Information

The alarm about linkdown of host link, as follows:

Handling Process

To collect storage system logs and analysis the log information about the host port connects with the FC fiber:

[2014-09-21 18:59:58]---->PLOGI:0x22122b00 0x0007f106 0x01290000 0x2e000000 0x0a97ffff 0x00000000 0x03000000 0x09080028 0x80000800 0x00ffffff 0x000007d0 0xc0507607 0x93340016

 // Host sends connection requests to the storage

[2014-09-21 18:59:58]<----LS_ACC(0x0):0x2307f106 0x00122b00 0x01980000 0x00000000 0x0a971155 0x00000000 0x02000000

[2014-09-21 18:59:58]<----PRLI(0x0):0x2207f106 0x00122b00 0x01290000 0x00000000 0x1154ffff 0x00000000 0x20100014 0x08002000 0x00000000 0x00000000 0x00000032 

// Storage actively sends PRLI connection request to the host

[2014-09-21 18:59:58]---->LS_RJT:0x23122b00 0x0007f106 0x01980000 0x05000000 0x11540a02 0x00000000 0x01000000 0x00091e00

// Host refuse PRLI connection request

[2014-09-21 18:59:58]<----LOGO(0x0):0x2207f106 0x00122b00 0x01290000 0x00000000 0x115fffff 0x00000000 0x05000000 0x00122b00 0x240ae097 0x96484f1f

// Storage port actively disconnect

 

When the host sends a connection request to the storage, the storage is unable to confirm whether the request is from the host, so it doesnt send a reply. When the storage actively sends PRLI connection request to the host, it is rejected by the host. So the connection establishment is failed and the storage actively disconnects. Its failed to build logical connection between host and storage.

To check the storages FC port connected with the host, which is default set as both the initiator and the target:

 

This setting of  front FC port will cause disconnection, so help customer to set  front FC port as target, then the issue is solved.

Root Cause

To check the storages FC port connected with the host, which is default set as both the initiator and the target:

In some complex network scenarios (such as multi-layer FC switch networking), this port mode setting (INI and TGT) may have compatibility issues. When AIX host is connected with Huawei storage by multi-layer FC switch, once the front FC port is set as both initiator and target, it will cause connection failed with a certain probability.

Solution

To set  front FC port as target:

1.      Step 1:

Run the command show port general physical_type=fc, to show all the FC port number. According to the connection between host and storage, confirm which ports (Role is INI and TGT) are connected to the host and record the corresponding port number.

2.      Step 2:

Run the command change port fc fc_port_id=xxx role=tgt (xxx is the port number recorded by step 1) , set all the FC ports to TGT.

Note: The command will cause the port link disconnected and automatically connected again. Please make sure that there are redundant links between the host and the other controllers. The FC port which is used by value_added feature cant be modified.

3.      Step 3:

After all the ports are modified, run the command show port general physical_type=fc. Make sure that Health Status value is Normal, Running Status value is Online and Role value is TGT.

4.      Step 4:

After all the FC ports of each controller are modified, wait 2 minutes. Run the command show controller general. Make sure that Health Status value is Normal, Running Status value is Online.

5.      Step 5:

Scan Lun on the host: cfgmgr -v

Suggestions

This issue is related with the special network environment. The storage port default configuration is both initiator and target. This may have compatibility issue during establishing a connection. This needs to implement the measure to avoid manually. Suggest that deal with similar connectivity issue, in priority to check whether the link is normal or not.

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