Dynamic TDR Analysis for Field Replaceable Unit Isolation
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Solution Overview
Problem
Current time-domain reflectometry (TDR) analysis in computer systems is ineffective for isolating field replaceable unit (FRU) defects in a running system, as it is typically performed during a quiet boot window, which does not reflect the actual system failure conditions, leading to incorrect repairs and increased repair times.
Innovation Solution
Implementing dynamic TDR analysis that allows for the isolation of defects in a running system by sparing bad lanes, executing TDR on them while the system is operational, and using the results to determine the faulty FRU without the need for initial microprogram load (IML) or repair windows, thereby reducing unnecessary evacuations and improving accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If TDR analysis is performed during quiet boot window, then system stability is maintained, but measurement precision is insufficient to detect actual failure conditions
Solution Approach 1:
The system dynamically switches between operational mode and TDR analysis mode, allowing the bus to transition from active signal transmission to a quiescent state for measurement. This dynamic approach enables accurate defect detection while maintaining overall system availability, as the bus can quickly return to operational mode after analysis.
Solution Approach 2:
The TDR analysis is performed periodically during brief quiescence windows when the bus is temporarily inactive, rather than requiring a complete system shutdown. This periodic measurement approach allows the system to maintain operation while obtaining accurate defect isolation data at regular intervals.
2Measurement precision
If TDR analysis is performed on running system, then measurement precision improves, but device complexity increases due to lane management requirements
Solution Approach 1:
The bus is divided into multiple independent lanes, allowing TDR analysis to be performed on individual lanes or groups of lanes while others remain operational. This segmentation enables selective testing without requiring complete system shutdown, and the system can manage different lanes in different states (operational or under test) simultaneously.
Solution Approach 2:
A lane management mechanism acts as an intermediary between the operational bus and the TDR analysis function, coordinating the switching of lanes between active and test modes. This intermediary manages the complexity of lane state transitions and ensures proper signal routing during analysis.
3Measurement precision
If bad lane is taken offline for TDR analysis, then defect isolation accuracy improves, but productivity decreases due to lane evacuation
Solution Approach 1:
The system temporarily discards the use of affected lanes during TDR analysis by taking them offline, performs the measurement to isolate defects, then recovers the lanes by returning them to operational mode. This temporary discarding and recovery approach enables accurate defect detection while minimizing impact on overall system productivity, as lanes are quickly restored after analysis.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables more accurate and timely identification of hardware defects, reduces repair time by eliminating incorrect evacuations, and allows for proactive monitoring of field bus anomalies, improving analysis precision through statistical sampling and reducing the need for critical repair windows.
Implementation Method 1
Time-domain reflectometry is a measurement technique used to determine the characteristics of electrical lines and/or circuits connected to the electrical line by observing reflected waveforms
Data Source
AI summary
A technique relates to dynamic time-domain reflectometry (TDR). A machine spares a bad lane in a bus. The bad lane is taken offline. TDR is dynamically executed on the bad lane while the bus is still in operation. A defect is isolated using results of the TDR.