Hybrid Single Double Chip Spare Memory Controller
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing memory systems face downtime issues due to single or multiple chip failures, which are not efficiently addressed by current Single Chip Spare (SCS) and Double Chip Spare (DCS) techniques, as SCS can only handle one failure while DCS incurs significant bandwidth inefficiencies.
Innovation Solution
A hybrid approach that initially operates in SCS mode, converting affected memory regions to DCS mode upon a single chip failure, maintaining full bandwidth for unaffected regions and accommodating additional chip failures with reduced bandwidth impact by dynamically redistributing cache lines across multiple memory busses or addresses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Single Chip Spare (SCS) mode is used, then the system can handle single chip failures, but it cannot accommodate multiple chip failures without complete memory module replacement
Solution Approach 1:
The system dynamically transitions between SCS and DCS modes based on detected chip failures. When a chip failure is detected, the system converts from SCS mode to DCS mode, allowing the memory subsystem to adapt its error correction capabilities in response to changing conditions rather than being static
2Reliability
If Double Chip Spare (DCS) mode is used, then the system can handle multiple chip failures, but it incurs significant bandwidth inefficiencies
Solution Approach 1:
The system applies DCS mode locally only to the specific memory region containing the failed chip, while the remainder of the memory system continues operating in SCS mode with full bandwidth efficiency. This localized approach avoids the global bandwidth penalties of traditional DCS while still providing protection for the affected region
3Reliability
If traditional DCS is implemented, then up to two chip failures can be accommodated, but all memory regions suffer bandwidth reduction
Solution Approach 1:
The memory system is segmented into affected and unaffected regions. The hybrid mode applies different error correction strategies to each segment: DCS to the affected region containing failed chips, and SCS to the unaffected regions. This segmentation allows selective application of bandwidth-intensive protection only where necessary
Data Source
AI summary
Techniques are provided for overcoming failures in a memory. One portion of the memory may operate in a single chip spare mode. Upon detection of an error in a single chip in the portion of the memory, a region of the portion of the memory may be converted to operate in a double chip spare mode. The memory may be accessed in both single and double chip spare modes.