IBM Midrange System DS4000 Series Hardware Manual page 119

There are two LEDs on each drive tray (see Figure 3-72 on page 100):
Drive Activity (number 1)
– On (not blinking): No data is being processed.
– Blinking: Data is being processed.
Drive Fault (number 2)
– Blinking: Drive, volume, or storage array locate function.
– On: A problem has occurred.
The Link Rate switch (number 6) should be set to 4 Gbps (depending on your configuration).
Rear view
This section describes the primary LEDs, controls, and connectors on the rear of the storage
expansion enclosure for all models. The back view in Figure 3-73 shows the following
components:
Fans and power supplies: Two removable power supply and fan unit FRUs, each
containing one power supply and two fans
ESMs: Two removable environmental services monitors (ESMs)
Figure 3-73 EXP5000 and EXP520 rear view
In Figure 3-73, you see the following LEDs and connectors:
ESM Power LED (number 1): Normally ON.
ESM Fault LED (number 2): ON when failures occur.
ESM Service Action Allowed (number 3): When ON, can be removed.
ESM Port 1 in Bypass (port is labeled 1A) (LED number 4): Normal status OFF when a
cable is connected and ON if no cable is connected. Problem status ON when a cable is
connected and a failure occurs.
Data Rate LEDs (number 5): 2 Gbps - one LED is lit. 4 Gbps - two LEDs are lit.
ESM Port 2 in Bypass (port is labeled 1B) (LED number 6): Normal status OFF when a
cable is connected and ON if no cable is connected. Problem status ON when a cable is
connected and a failure occurs.
ESM ports 3 and 4 (LEDs number 7, 8, and 9) are reserved for future use.
Chapter 3. IBM System Storage DS4000 and DS5000 hardware
101