Technical Advisory

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

Intel Technical Advisory TA-1052-1

5200 NE Elam Young Parkway

Hillsboro, OR 97124

March 11, 2014

Intel® RAID Controller with Intel

RAID Maintenance Free Backup Unit

(RMFBU) May Remain in Write Back Mode With a Damaged RMFBU

Products Affected

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

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

Backup Unit as an accessory are affected by this issue:

RS25AB080 RS25SB008 RS25SB008 with AXXRPFKHA2

RMS25CB080 RMS25CB040 RMST3CB080

RMS25PB080 RMS25PB040 RMST3PB080

RS25ZB040 RS25ZB080LX

RS3DC080 RS3DC040

Description

Intel has found that in the rare occurrence that a RAID Maintence Free Backup Unit (RMFBU) has damaged electrical

components, a RAID controller and attached RMFBU listed above that has an array set to allow for Write Back Cache

may remain in Write Back mode when a scheduled RMFBU Learn cycle fails to successfully complete rather than being

changed to Write Through mode as desired.

During a scheduled learn cycle, if user data buffered in write back cache of the RAID controller has not yet been

committed to disk and the RMFBU has damaged electronics, the data in cache could be lost in the event of a

unexpected power interruption.

Atypical damage to the electronics of the RMFBU is required for this undesired behavior to occur. An RMFBU subject

to normal service wear is not expected to be impacted by this issue. In the case that an RMFBU wears to the point that

it can no longer hold sufficient charge, the RMFBU will be marked by RAID firmware as failed and the RAID volume

cache policy will be changed to Write Through mode until the RMFBU is replaced.

Root Cause

Intel has determined that when an RMFBU with damaged electrical components is used, the behavior of the RAID

firmware managing the RMFBU may fail to detect the error and may fail to change the RAID volume’s cache property to

Write Through mode, and that the damaged RMFBU may not be able to provide sufficient charge to sustain a cache

offload should the system power be unexpectedly interrupted.

Corrective Action / Resolution

Intel has developed a RAID controller firmware that will resolve this issue by properly setting the RAID volume’s cache

property to write through mode when the RAID firmware fails to successfully complete a learn cycle. Once the RMFBU

successfully completes the learn cycle the cache property will be returned to Write Back cache mode. This firmware

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This Technical Advisory describes an issue which may or may not affect the customer’s product Intel Technical Advisory TA-1052-1 5200 NE Elam Young Parkway Hillsboro, OR 97124 March 11, 2014 Intel® RAID Controller with Intel® RAID Maintenance Free Backup Unit (RMFBU) May Remain in Write Back Mode With a Damaged RMFBU Products Affected The following Intel® Controllers that ship with a RAID Mantenance Free Backup Unit (RMFBU) or Intel® RAID modules or Intel® RAID Controllers that support an AXXRMFBU2, AXX
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update for the controllers listed in the table below is available on the Intel support website (Flash package v23.22.00020 with firmware version 3.340.55-3173). RS25AB080 RS25SB008 RMS25CB080 RMS25CB040 RMST3CB080 RMS25PB080 RMS25PB040 RMST3PB080 Follow-on firmware updates for these controllers will also include these changes.
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