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. Note:  Before you change the system layer, the following conditions must be met: For more information about layers and how to change them, see  IBM Knowledge Center . 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. 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. 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. iSCSI external storage controllers Fibre Channel external storage controllers GLYPH<SM590000> No host object can be configured with worldwide port names (WWPNs) from a Storwize  family system. GLYPH<SM590000> No system partnerships can be defined. GLYPH<SM590000> No Storwize family system can be visible on the SAN fabric. 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> Figure 6-49 Discover storage menu Chapter 6. Storage pools  229