Fujitsu ETERNUS DX S5 Series Operation Manual (Basic page 58

4. Component Expansion/Function Enhancement
Installing Additional Drive Enclosures
10
In the [Disable IOM#1] screen, click the [Next>>] button.
The process to disconnect IOM#1 starts.
When the disconnection process is complete, the [Detach Cable] screen appears.
11
Disconnect the cables from I/O module line 1.
Remove the cable that connects the DI (OUT) port of CM#1 in the controller enclosure and the DI (IN) port
of IOM#1 in the drive enclosure, which is nearest to the drive enclosure that is to be added.
58 Operation Guide (Basic)