SSD Backend Wear Balancing Through Dynamic Command Rerouting
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Solution Overview
Problem
Existing data storage management systems face challenges in evenly distributing traffic across domains of solid state drives (SSDs), leading to uneven wear and reduced lifespan due to imbalanced traffic conditions, and lack flexibility in managing logical block addresses (LBAs) and excess movement, which can result in premature end-of-life for the entire drive.
Innovation Solution
A method and system for rerouting commands between domains within a storage device by using logical-to-physical (L2P) look-up tables (LUTs) and reroute tables to balance wear levels, involving the use of rerouting read, write, and garbage collection commands to redistribute logical addresses and update L2P information across domains.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If global wear leveling is used to split work evenly across domains, then each domain reaches end of life endurance at the same time, but the system cannot address different traffic conditions and is not flexible when uneven traffic distribution changes
Solution Approach 1:
The patent implements dynamic wear leveling by monitoring actual domain wear levels and adjusting command routing in real-time. The system dynamically modifies the distribution of read/write commands based on current wear states, allowing the system to adapt to changing traffic patterns and wear conditions across domains, rather than using a static even split.
Solution Approach 2:
The system incorporates feedback mechanisms where the controller monitors wear levels across domains and uses this information to adjust command routing decisions. This feedback loop enables the system to respond to actual wear conditions and traffic patterns, making the wear leveling adaptive and flexible rather than fixed.
2Ease of operation
If domains are separately managed with independent L2P LUTs, then each domain can be independently controlled, but movement and excess logical block addresses cannot be tracked and it is not clear how much data a target domain can support
Solution Approach 1:
The patent introduces an intermediary mechanism in the form of a shared wear level tracking structure and inter-domain communication protocol. This intermediary enables domains to maintain independent control through their own L2P LUTs while simultaneously tracking LBA movements and wear levels across domain boundaries, resolving the information loss problem.
Solution Approach 2:
The system implements a universal wear level management mechanism that serves multiple functions: tracking wear across domains, monitoring LBA movements, determining target domain capacity, and coordinating wear leveling operations. This multi-functional approach eliminates the need for separate tracking mechanisms while maintaining independent domain control.
3Reliability
If commands are routed to the domain with the least wear, then wear distribution is balanced, but the system requires complex monitoring and adjustment mechanisms
Solution Approach 1:
The system changes the routing parameter from static even distribution to dynamic wear-based distribution. By monitoring wear levels as a key parameter and adjusting routing decisions based on this parameter, the system achieves better wear balance. The controller modifies command routing based on real-time wear state information, enabling adaptive load distribution.
Data Source
AI summary
Methods and devices are provided in which a controller of a storage device receives a command. A logical capacity of the storage device is split into domains. The controller determines a logical address associated with the command. The logical address is associated with a first domain of the storage device. The command is rerouted from first resources of the controller attributed to the first domain to second resources of the controller attributed to a second domain of the storage device, based on a physical address associated with the logical address.