Flash Storage Block Management for Wear Leveling
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Solution Overview
Problem
Existing flash memory devices face limitations in the number of erasure cycles for physical blocks, leading to data storage failures, and existing solutions often require replacing entire devices even when usable blocks remain, resulting in inefficient use of resources.
Innovation Solution
A storage apparatus utilizing multiple flash memory devices with a RAID controller that manages virtual drives and logical storage areas, allowing for the continuous use of non-failed blocks by reassigning logical block mappings and utilizing unused blocks to extend the life of flash memory devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the number of erasure cycles for physical blocks is increased to improve storage capacity utilization, then resource utilization improves, but the reliability of data storage deteriorates due to block failures
Solution Approach 1:
The system changes the management parameter from device-level replacement to block-level management. By tracking the state of individual physical blocks and dynamically adjusting which blocks are available for logical storage areas, the system maximizes utilization of functional blocks while isolating failed blocks, thus resolving the contradiction between capacity utilization and reliability
Solution Approach 2:
The system segments the flash memory device into individual physical blocks and manages them independently. By dividing the storage device into manageable block units that can be individually monitored and reassigned, the system can continue using non-failed blocks even when some blocks fail, thereby maintaining both high utilization and reliability
2Reliability
If entire flash memory devices are replaced when a failure occurs in any block, then data reliability is maintained, but resource utilization deteriorates due to waste of remaining usable blocks
Solution Approach 1:
The system extracts the failed physical blocks from the active storage pool and isolates them, while keeping the remaining functional blocks in service. This allows the system to maintain reliability by removing failed blocks without discarding the entire device, thus preventing waste of usable blocks
Solution Approach 2:
The system implements dynamic block management where the availability of physical blocks is continuously monitored and adjusted. When blocks fail, the system dynamically reassigned logical storage areas to different physical blocks, enabling flexible adaptation that maintains reliability while maximizing resource utilization
3Quantity of substance
If flash memory devices with higher density are used to improve storage capacity, then storage capacity increases, but the number of erasure cycles decreases leading to reduced device lifespan
Solution Approach 1:
The system changes from managing storage at the device level to managing at the block level within devices. By implementing wear leveling algorithms and tracking individual block erasure counts, the system can distribute write operations across multiple blocks and replace only failed blocks rather than entire devices, thereby extending the effective lifespan of high-density storage devices
Solution Approach 2:
The system performs preliminary monitoring of block health and erasure cycle counts. By detecting potential failures before they occur and proactively managing block allocation, the system can prevent catastrophic device failure and extend the operational lifespan of high-density flash memory devices
Data Source
AI summary
A storage apparatus includes: a plurality of flash memory devices each including: a plurality of flash memory chips each including a plurality of physical blocks being data erasure units; and a flash controller configured to provide logical storage areas by associating at least one of the plurality of physical blocks with the logical storage areas; and a RAID controller configured to: manage a plurality of virtual drives each including a part of the logical storage areas provided by each of the plurality of flash memory devices; and control the plurality of virtual drives as a RAID group.