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Cisco Bug: CSCvs97236 - Workaround for Patrol Scrub Mis-Identification Needed on Server EX with IVB Processor

Last Modified

Sep 02, 2020

Products (1)

  • Cisco Unified Computing System

Known Affected Releases

4.1(1.11)B

Description (partial)

Symptom:
When the CPU iMC (Integrated Memory Controller) Patrol Scrubber detects an Uncorrectable ECC error, it logs a truncated system address (4KB page boundary) to the Machine Check Banks.
When the iMC Demand Scrubber detects an Uncorrectable ECC error, it logs the full 'cache line' (non-truncated) address to the Machine Check Banks.

M4 platforms use this truncated memory address to forward translate the address to a physical DIMM. Depending on system population and configuration, it is possible that the SEL message logging the Uncorrectable ECC error will not point to the correct DIMM. 
Uncorrectable ECC errors detected during Demand scrub are correctly translated to physical DIMM.

Patrol Scrub - Proactive sweep of all system memory searching for and attempting to repair any errors found
Demand Scrub - At the time of a memory read/write, the requested data is checked and any errors are attempted to be corrected

Conditions:
M4 UCS-C Rack Servers
Uncorrectable ECC error detected during Patrol Scrub
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