Surplus Erase Block Pairing for Superblock Formation
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Solution Overview
Problem
Flash storage devices face reduced usable capacity and performance due to the inefficient management of bad blocks, leading to a depletion of the spare pool and surplus blocks, which limits superblock formation and storage device capacity.
Innovation Solution
The controller in the storage device identifies and manages bad blocks by switching single plane good blocks to a surplus state instead of adding them to the spare pool, and pairs surplus blocks from both planes to add to the spare pool, allowing for continued superblock formation even after numerous bad blocks occur, thereby increasing storage device capacity and life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If single plane good blocks are added to the spare pool after bad block identification, then the spare pool depletes quickly, but this conventional approach reduces usable capacity and limits superblock formation
Solution Approach 1:
The patent recovers surplus blocks by pairing them from different planes and adding them to the spare pool. Instead of discarding surplus blocks or adding single-plane blocks directly to the spare pool (which depletes it quickly), the system recovers and pairs surplus blocks from both planes, thereby extending the spare pool's utility and enabling continued superblock formation.
2Reliability
If surplus blocks are not paired and added to the spare pool, then the spare pool is maintained, but storage device capacity and usable space are reduced
Solution Approach 1:
The patent merges surplus blocks from different planes by pairing them together and adding the pairs to the spare pool. This combining approach maintains the reliability of the spare pool while increasing storage device capacity, as paired surplus blocks from both planes are utilized together rather than being left unused or added as single-plane blocks.
3Reliability
If conventional bad block management is used, then bad blocks are identified and marked, but this leads to depletion of surplus blocks and limits device life
Solution Approach 1:
The patent enables continuous superblock formation by pairing surplus blocks from both planes and adding them to the spare pool. This continuous utilization of surplus blocks extends device life, as the system can maintain operational capacity throughout the device's lifecycle rather than depleting surplus blocks early on.
Data Source
AI summary
Aspects of a storage device including at least one die and a controller are provided that allow superblock formation using surplus block pairs when bad blocks occur. After the controller forms a superblock including a first block in a first plane of the die and a second block in a second plane of the die, the controller identifies the first block as a bad block and switches the second block into a surplus state (or vice-versa). The controller then forms a new superblock from blocks in a spare pool. When the number of blocks is equal to a superblock threshold, the controller attempts to pair the surplus block with another surplus block from the opposite plane according to a die sequence. If the attempt to pair is successful, the controller adds the pair to the spare pool; otherwise, the surplus block is not added to the spare pool.