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LUNs that are Split and then Mapped to the Host Server cannot be Identified by the Linux OS

Publication Date:  2012-07-20 Views:  22 Downloads:  0
Issue Description
A host server running the Linux Red Hat 4.3 OS is connected to the S5000 by using the QLOGIC FC HBA and a single link. After two LUNs are configured on the S5000 (LUN A has 1 GB and LUN B has 2 GB) and mapped to the host server, the two LUNs are formatted and can be normally used. LUN B is split to two LUNs, LUN B and LUN C, of 1 GB capacity each. The two LUNs are mapped to the host. The disk information is checked without service interruption. The original two LUNs are still displayed and the second LUN still has 2 GB. The disk information is not updated.
Alarm Information
Handling Process
Run the ql-dynamic-tgt-lun-disc-2.3 QLOGIC script on the host server to update the disk information without service interruption. The procedure is as follows:
[root@T8223t1-slot10 ql-dynamic-tgt-lun-disc-2.3]# ./  -i
Please make sure there is no active I/O before running this script
Do you want to continue: (yes/no)?  y
 Welcome to QLogic LUN Scan Utility
        1: ALL HOSTS SCAN
        4: SET MAX LUN's TO SCAN (Current: 256)
        6: QUIT 
 Please select one of the options above : 2 
 Issuing LIP on host17
Scanning HOST: host17
No devices attached to HOST: host17
Issuing LIP on host18
Scanning HOST: host18
According to verification, this operation does not affect the other disk services. Run the fdisk -l command to view LUN C (1 GB), but LUN B still has 2 GB. The information is not updated. Format LUN B whose actual capacity is 1 GB. After that, the capacity is correctly displayed.
Root Cause
Even though the split LUNs are mapped to the host server, the Linux OS cannot update the LUN information in real time. The storage system needs to update the information about the HBA.
The solution mentioned above is a method for emergency, for example, the original LUNs need to be split when customer’s services cannot be interrupted. If services can be suspended for a short time, you can solve the problem by restarting the host server or uninstalling and installing the FC HBA.