Chapter 6. Storage pools 229
Then, the system is able to see external Storwize systems as storage controllers and can 
virtualize LUs that are provided by them. 
You also get a warning that your Storwize is in a storage layer if you try to add an iSCSI 
storage controller with the GUI. The system prompts you to convert the system to replication 
layer automatically.
To switch IBM Storwize V7000 system layer, you can also use chsystem CLI command, as 
shown in Example 6-23. If executed successfully, it returns no output.
Example 6-23   Changing system layer
IBM_Storwize:ITSOV7K:superuser>lssystem |grep layer
layer storage
IBM_Storwize:ITSOV7K:superuser>chsystem -layer replication
IBM_Storwize:ITSOV7K:superuser>
For more information about layers and how to change them, see IBM Knowledge Center.
Fibre Channel external storage controllers
A controller connected through Fibre Channel is detected automatically by the system, 
provided that the cabling, the zoning, and the system layer are configured correctly.
If the external controller is not detected, ensure that the Storwize V7000 is cabled and zoned 
into the same storage area network (SAN) as the external storage system. Check that layers 
are set correctly on both virtualizing and virtualized systems if they belong to the IBM 
Storwize family. 
After the problem is corrected, use Actions → Discover Storage button found in Pools → 
External Storage, as shown in Figure 6-49, to rescan the Fibre Channel network.
Figure 6-49   Discover storage menu
This action executes CLI command detectmdisk. It returns no output. Although it might 
appear that the command has completed, some extra time might be required for it to run. 
detectmdisk is asynchronous and returns a prompt while the command continues to run in 
the background.
iSCSI external storage controllers
Unlike Fibre Channel connections, you must manually configure iSCSI connections between 
the Storwize V7000 and the external storage controller. Until you do this, the controller is not 
listed in the External Storage pane.
Note: Before you change the system layer, the following conditions must be met:
/SM590000No host object can be configured with worldwide port names (WWPNs) from a Storwize 
family system.
/SM590000No system partnerships can be defined.
/SM590000No Storwize family system can be visible on the SAN fabric.