Technical Advisory 1050

This Technical Advisory describes an issue which may or may not affect the customer’s product

Intel Technical Advisory

TA-1050-2

5200 NE Elam Young Parkway

Hillsboro, OR 97124

March 12, 2014

Intel

RAID Maintenance Free Backup Unit (AXXRMFBU2) Cache

Offload Module failures may occur with an AC power loss while the

power supplies are operating in Cold Redundancy mode

Products Affected

All Intel server systems configured with both an Intel

RAID Maintenance Free Backup Unit (AXXRMFBU2) and dual

750W AC Power Supplies.

Description

Intel has investigated a customer reported issue where the cache off-load module of the Intel

RAID Maintenance Free

Backup Unit (AXXRMFBU2) failed to write back saved data during an AC power cycling test.

All of the following must be true for this issue to occur:

 The system is configured with an Intel

RAID Maintenance Free Backup Unit (AXXRMFBU2)

 Installed power supplies are 750W AC (part number E98791-009 or earlier)

 One of the installed power supplies is operating in Cold Redundant mode

when AC power loss occurs

 Both power supplies exhibit an AC loss at the same time - single or dual power source

 The output DC load on the system ranges from 120W – 216W

Root Cause

Intel has determined that the cache off-load module failure was due to a power/reset timing issue that may occur when

AC power is lost. During an AC power loss event, the system power drops below its threshold before the system is able

to assert a PCIe_RST# signal, causing a race condition to occur. The race condition prevents the RMFBU2 from

initiating a memory write-back operation.

Note: A system with power supplies operating in a standard output redundant (1+1) or non-redundant (2+0) mode, will

not be affected by this issue. Only systems with a power supply operating in a low power cold redundant mode may be

affected by this issue.

Cold Redundancy Mode - Power supplies that support cold redundancy can be enabled to go into a low-power state (that is, cold

redundant state) in order to provide increased power usage efficiency when system loads are such that both power supplies are not

needed. When the power subsystem is in Cold Redundant mode, only the needed power supply to support the best power delivery

efficiency is ON. Any additional power supplies; including the redundant power supply, is in Cold Standby state

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This Technical Advisory describes an issue which may or may not affect the customer’s product Intel Technical Advisory TA-1050-2 5200 NE Elam Young Parkway Hillsboro, OR 97124 March 12, 2014 Intel® RAID Maintenance Free Backup Unit (AXXRMFBU2) Cache Offload Module failures may occur with an AC power loss while the power supplies are operating in Cold Redundancy mode Products Affected ® All Intel server systems configured with both an Intel RAID Maintenance Free Backup Unit (AXXRMFBU2) and dual 750W AC P
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Corrective Action / Resolution Intel has released new power supply firmware (ver 85.**.100) that will prevent the power race condition from occurring. • Customers that decide they want to update their systems to address this issue can do so by updating the system BMC Firmware to revision 01.20.5793 or later which incorporates the new power supply firmware. The power supply firmware is updated automatically with a BMC firmware update.