Technical Advisory

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

Intel Technical Advisory TA-1055-1

5200 NE Elam Young Parkway

Hillsboro, OR 97124

May 1, 2014

Intel

RAID Maintenance Free Backup Unit (RMFBU) Charge Level

Threshold Update to Resolve a Failure to Complete a Relearn issue

and Extend the Usable Life of the Unit.

Products Affected

The following Intel® Controllers that ship with a RAID Maintenance Free Backup Unit (RMFBU) or Intel® RAID modules

or Intel® RAID Controllers that support an AXXRMFBU2, AXXRMFBU3, and AXXRMFBU4 RAID Maintenance Free

Backup Unit as an accessory are affected by this issue:

RS25AB080 RS25SB008

RMS25CB080 RMS25CB040 RMST3CB080

RMS25PB080 RMS25PB040 RMST3PB080

RS25ZB040 RS25ZB080LX

RS3DC080 RSDC040

Description

Intel has observed that on a small percentage of units that the threshold for charge on the gas gauge subassembly

within the RAID Maintenance Free Backup Unit (RMFBU) may not provide enough margin to accurately judge the health

of the Super Capacitors. This can result in a failure of the RMFBU to complete a learn cycle. A modification to the gas

gauge charge level thresholds will resolve this issue and may also improve the usable life of the Super Capacitor.

Root Cause

The firmware that supports the RMFBU gas gauge circuitry includes threshold settings that control the charge level of

the Super Capacitors. The firmware will increase charge voltage as the Super Capacitors wear in order to maintain a

sufficient charge level to support a cache offload in the event of a power outage. To measure the health and wear of

the Super Capacitors, the RMFBU gas gauge firmware initiates a learn cycle during which time its capability to hold a

charge is measured. Based on information obtained from the learn cycle, the firmware will select the proper set of

charge level thresholds. Intel has determined that improvements are needed to these charge level thresholds to allow a

learn cycle to complete when one or more electrical components of the gas gauge circuitry are operating close to their

marginal limit. Investigation of learn cycle threshold behavior has identified opportunities to improve the usable life span

of the Super Capacitors.

Corrective Action / Resolution

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This Technical Advisory describes an issue which may or may not affect the customer’s product Intel Technical Advisory TA-1055-1 5200 NE Elam Young Parkway Hillsboro, OR 97124 May 1, 2014 Intel® RAID Maintenance Free Backup Unit (RMFBU) Charge Level Threshold Update to Resolve a Failure to Complete a Relearn issue and Extend the Usable Life of the Unit.
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Charge level thresholds have been improved as described in the table below: 1 2 3 4 Improvement Eliminate the condition where a known good Super Capacitors will be declared as “Bad” prematurely when gas gauge bumps the charge voltage to next level as the Super Capacitors age. Eliminate reporting of Super Capacitors failures when a learn cycle fails to complete successfully due to component tolerances.
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