Source
RETAIN tip H133777

Symptom
Servers with hot-swap backplanes may experience intermittent drive errors, defunct (DDD) drives that don't spin down or drive LEDs that don't blink when a drive has failed.

Affected configurations
The system is an 8640, 8641, 8642 or 3518 with one or more hot swap backplanes installed.

Solution
Check the Backplane Address Jumper:
1. Shutdown the operating system
2. Power off the server.
3. Verify the Backplane Address Jumper configuration:

a. For ALL 8640 and 8641 backplanes: Jumpers should NOT be present on the pins for Bank0, Bank1, or Bank2 on any backplane. Refer to Figure 1. The PC Server 520 (8641) may have shipped with a backplane address jumper installed; it should be removed.

b. For 8642 and 3518 backplanes: Each backplane MUST have a unique address. A jumper should be present on the pins for Bank0, Bank1, OR Bank2 depending on the backplane's location within the server or expansion enclosure. Refer to Figure 1 and Table 1 below to determine the correct jumper setting for an 8642 or 3518 backplane.

Figure 1

Backside of backplane

Table 1

NOTE: The documentation in the Server 520 User's Handbook, part number 62H7096, page 177 is incorrect. Backplane address jumpers should NOT be installed on any Server 520 backplanes.