In an IBM ProtecTIER environment, administrators can now manage the visibility of specific devices to specific hosts. This feature is called LUN masking. This e-Learning module explains how LUN masking works and the general steps to define a LUN masking group.
Let us look at an example to understand how LUN masking works. You are an administrator managing a ProtecTIER server environment. The server includes several devices, including drives and robots. Each device is assigned a LUN. In this example, you are managing two hosts. Each host has two ports. Each port has a unique worldwide name, or WWN. One of the ports on each host acts as a host initiator. The host initiator uses the port WWN for identification. By default, all the devices within this example ProtecTIER environment are visible to all the hosts. For security purposes, you need to hide some of the devices from one of the ports. To do this, you must create a LUN masking group and assign the host initiator and specific devices to that group, so that the selected devices are only visible to the selected host. Note that LUN masking can only be performed on virtual tape library systems.
There are several steps to perform LUN masking. First, open the ProtecTIER Manager and select VT -> Host initiators management. A list of available host initiators is displayed. For the LUN masking group you are defining, select one or more host initiators from the list, or add host initiators by entering the appropriate WWNs. You can also enter an alias to the WWN.
Now that you have identified a host initiator, you can create a LUN masking group. Select VT -> LUN Masking -> Configure LUN Masking groups. Click Add and enter a name for the group.
Click Add in the Selected Host Initiators pane to add one or more host initiators to the group.
Click Add at the bottom of the Library Mappings pane to select the libraries that contain the devices you want to make visible to the hosts you just identified. Then select the devices to assign to the LUN masking group.
On this pane, you can also reassign LUN values. This feature sequentially re-numbers all the LUN values of the available devices in the group.
After you create a LUN masking group, you can modify that group by adding or removing devices, libraries of devices, or host initiators. Note that a specific host initiator can only belong to one LUN masking group, but you can have multiple host initiators in a group and multiple groups. You can also enable and disable LUN masking at any time. To do this, select VT > LUN Masking > Enable/Disable LUN Masking and make your selection. The system then rescans the devices from the host systems, so that the host has the most up-to-date information.
This e-Learning module provided a general overview of LUN masking. For more information, see the LUN masking topics in this information center.