Reason why redundant disks appear in an AIX application server on an IP SAN network

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The AIX application server is connected to the Ethernet switch through a network cable. The switch is connected to two iSCSI host ports on the same controller of the storage device through two network cables. When a LUN is mapped to the AIX application server, the AIX application server detects redundant disks.

To enhance the data transfer reliability, an application server and a storage array are usually connected over multiple paths. If the multipathing software is unavailable, those multiple paths translate into multiple redundant disks, which confuse the actual number of disks.

In the Ethernet networking, the AIX application server does not support the multipathing software. Therefore, redundant disks are detected on the AIX application server.

On a Fibre Channel network, AIX application servers support the multipathing software.

Other related questions:
Whether the storage system supports the VMware ESX 4.1 application server in an IP-SAN network
About whether the S2600 V100R001 storage system supports the VMware ESX 4.1 application server in an IP-SAN network, see FAQ-Does the S2600 V100R001 support the VMware ESX 4.1 application server in an IP SAN network

Why do multiple mock disks appear on the application server after the log on operation is repeatedly performed?
Every time when the log on operation is performed on an AS, a session is established between the AS and the storage system. Based on the session, the operating system (OS) of the AS scans the mapped LUNs. If the multipathing software is not installed, the OS cannot determine whether the LUNs scanned from several physical paths are the same LUN, and assumes them as different LUNs (the number of LUNs is equal to the times of performing the log on operation); therefore, multiple mock disks appear on the AS. If the multipathing software is installed, it can determine whether the LUNs in different sessions are the same LUN by analyzing the world wide name (WWN) of each LUN, and eliminates the mock disks.

HUAWEI SAN Storage Host Connectivity Guide for AIX
You can obtain HUAWEI SAN Storage Host Connectivity Guide for AIX from .

Why the number of hard disks scanned by the application server is a multiple of the number of hard disks mapped to the application server?
The multipathing software is not installed. If the multipathing software is not installed, the OS cannot determine whether the LUNs scanned from several physical paths are the same LUN, and assumes them as different LUNs; therefore, multiple mock disks appear on the AS. If the multipathing software is installed, it can determine whether the LUNs in different sessions are the same LUN by analyzing the world wide name (WWN) of each LUN, and eliminates the mock disks. In this way, the number of hard disks scanned by the AS is the number of LUNs actually mapped to the AS. You can obtain the installer of the multipathing software from the delivery-attached CD-ROM and install the program according to the actual OS.

Method used to safely delete a LUN mapping from an AIX application server
Perform the following operations to delete a LUN mapping from an AIX application server: On the storage device side, delete the LUN mapping with the AIX application server. On the AIX application server side, run rmdev -dl diskName to delete the virtual disk of the mapped LUN. For example, you can run rmdev -dl disk3 to delete the virtual disk disk3. Note: If the virtual disk is not deleted and a new LUN is mapped to the AIX application server, a fault occurs, indicating that the virtual disk path is missing. Rectify the fault as follows: Unmount the file systems of the original LUN and the newly mapped LUN. Close the volume group of the newly mapped LUN. Delete the virtual disks of the original LUN and the newly mapped LUN. Run cfgmgr to re-scan for disks.

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