M4000 / M5000: SCF-8004-EC - Lost internal disks / DVD / Tape drive and voltage errors on Fan Backplane

Asset ID:	1-72-1020968.1
Update Date:	2011-05-18
Keywords:

Solution Type Problem Resolution Sure

Solution 1020968.1 : M4000 / M5000: SCF-8004-EC - Lost internal disks / DVD / Tape drive and voltage errors on Fan Backplane

Applies to:

Sun SPARC Enterprise M4000 Server
Sun SPARC Enterprise M5000 Server
All Platforms

Symptoms

Loss or no access to all internal Hard Disks / DVD / Tape resulting in

Hung domain
Domain hang followed by an attempt to reboot
Unable to boot from HDD or DVD
Unable to install OS to HDD from network
Depending on failure mode, XSCF> showdisks / # format may or may not show the devices.
Errors logged

Example: (XSCF> showlogs error )

Status: Information FRU: /HDD#2,/IOU#1 Msg: Boot process failed
Status: Alarm FRU: /FANBP_C Msg: Critical low voltage error

Fan backplane faulted or degraded
Fault Event SCF-8004-EC
XSCF> fmdump -V

one or several of the following
event ereport.chassis.power.uvf@chassis/fanbp_b/v_3_3v;
event ereport.chassis.power.uvf@chassis/fanbp_b/v_5_0v;
event ereport.chassis.power.uvf@chassis/fanbp_b/v_12_0v;
event ereport.chassis.power.uvf@chassis/fanbp_b/v_12_0v_hdd;
or
event ereport.chassis.power.uvf@chassis/fanbp_c/v_3_3v;
event ereport.chassis.power.uvf@chassis/fanbp_c/v_5_0v;
event ereport.chassis.power.uvf@chassis/fanbp_c/v_12_0v;
event ereport.chassis.power.uvf@chassis/fanbp_c/v_12_0v_hdd;

Fault Event SCF-8004-DQ
XSCF> fmdump -V

one or several of the following:
event ereport.chassis.power.vw@chassis/fanbp_b/v_3_3v;
event ereport.chassis.power.vw@chassis/fanbp_b/v_5_0v;
event ereport.chassis.power.vw@chassis/fanbp_b/v_12_0v;
event ereport.chassis.power.vw@chassis/fanbp_b/v_12_0v_hdd;
or
event ereport.chassis.power.vw@chassis/fanbp_c/v_3_3v;
event ereport.chassis.power.vw@chassis/fanbp_c/v_5_0v;
event ereport.chassis.power.vw@chassis/fanbp_c/v_12_0v;
event ereport.chassis.power.vw@chassis/fanbp_c/v_12_0v_hdd;

Changes

Component failure

Cause

Technical background

There are several failure modes not detectable by the XSCF software that can cause complete or partial loss of all internal hard disks, DVD drive and tape unit. These failure modes are related to low (or zero) voltage on one or several of the voltages supplied to the devices.

To understand this it is useful to know about the way power is distributed to these devices.

48V from the main power supplies is first brought via the power backplane to the fan backplane where several conversions are done.
The fan backplane then supplies the devices via their respective backplanes.

There are 4 DC/DC converters on the fan backplane

48V to 12V for the drives (v_12_0v_hdd)
48V to 12V for the DC/DC converters (v_12_0v) - this is an intermediate voltage that does not leave the fan backplane
(v_12_0v) to 3.3V for the device backplanes (v_3_3v)
(v_12_0v) to 5.0V for the drives (v_5_0v)

A "spider" cable harness (M5000: 22 wires, M4000: 18 wires) connects the fan backplane to 48V from the power backplane and the (v_12_0v_hdd), (v_3_3v), (v_5_0v) to the device backplanes. This connector is marked "J0101" on the fan backplane.

The power path

48V --> power backplane --> cable harness --> fan backplane with DC/DC conversions --> cable harness --> device backplane --> device

There are 3 types of device backplanes:

Dual HDD backplane (one in M4000, 2 in M5000)
DVD backplane
Tape backplane

All backplanes take their power from the same source on the fan backplane and via the same "J0101" connector. For their power, they are connected in parallel.

At this point it should become clear that a failure of any of the 4 voltages will affect all devices.

Either a failed DC/DC converter or a short circuit in any of the devices or their backplanes can bring one or several of the voltages down and cause loss of operation of the HDD /DVD/Tape.

Solution

Resolution steps are described in this section

The general principle to is to eliminate in a step by step fashion the piece of hardware that causes the fault.

First suspect: Fan backplane.
Second suspects : devices (HDDs / DVD / Tape)
Third suspect: Device backplanes

Steps to follow

1. Replace fan backplane.

M4000: Part Number 541-0909
M5000: Part Number 541-0848

2. XSCF> poweron -a

3. Check that the fan backplane is not faulted anymore

4.Verify if devices operate normally

If yes, go to step 13.

5. If the problem persists

XSCF> poweroff -a

unplug one (or next) device HDD / DVD / TAPE
Go to service mode

SERVICE> clearfault /FANBP_B (M4000)
SERVICE> clearfault /FANBP_C (M5000)
XSCF> poweron -a

6. If the problem persists, go back to previous step.

7. If the low voltage problem disappears
- replace the device that causes the fault.

8. Verify if devices operate normally

If yes, go to step 13.

9. If the problem persists

XSCF> poweroff -a

unplug one (or next) device backplane connector HDD / DVD / TAPE (large 4-wire connectors)
Go to service mode

SERVICE> clearfault /FANBP_B (M4000)
SERVICE> clearfault /FANBP_C (M5000)
XSCF> poweron -a

10. If the problem persists, go back to previous step.

11. If the low voltage problem disappears

replace the device backplane that causes the fault.

12. If the problem persists, get help from senior engineers.

13. Clear any remaining fault that can be related to the initial issue:

SERVICE> clearfault (/FANBP_A /OPNL ..)

Additional Information

Find related information in troubleshooting document "Sun SPARC Enterprise(R) Mx000: Information & Troubleshooting certain Power faults" (Doc ID 1006872.1)

OPL, disk, lost, HDD, DVD, tape, hang, fan, backplane, voltage

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