Storage Controller Block Liveness Detection Secure Deletion
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Solution Overview
Problem
Current computer storage devices lack secure deletion capabilities, as they cannot reliably erase deleted data due to limitations in file systems and disk interfaces, leading to potential data recovery from unoverwritten blocks in sensitive environments.
Innovation Solution
A storage device with a controller that interprets file system metadata to determine block liveness, enabling secure deletion through off-track writing and multiple overwrites without modifying the disk interface or file system, allowing for secure data destruction and optimization techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If secure deletion is implemented by modifying the file system to erase blocks whenever a logical data file is deleted, then data security is improved, but device complexity and interface requirements increase
Solution Approach 1:
The patent introduces an intermediary layer between the file system and storage device - a secure deletion module that monitors file system operations and independently manages block erasure. This module intercepts delete operations and coordinates the erasure process without requiring modifications to the file system interface, thus maintaining simplicity while achieving secure deletion
Solution Approach 2:
The storage device is equipped with self-service capabilities to perform secure deletion autonomously. The device monitors its own block usage through metadata and automatically erases deleted blocks using off-track writing and multiple overwrites without external intervention, reducing interface complexity while ensuring data security
2Reliability
If off-track writing and multiple overwrites are implemented for secure deletion, then data security is improved, but storage device performance and write amplification are worsened
Solution Approach 1:
The patent implements preliminary identification of deleted blocks through metadata monitoring. When a file is deleted, the system proactively identifies the associated blocks before they are needed for new data, allowing secure erasure to be performed at an optimal time without interfering with active I/O operations, thus minimizing performance impact
Solution Approach 2:
The secure deletion process is implemented as a periodic background operation rather than synchronous with user I/O. The system periodically scans for deleted blocks and performs off-track writing and overwrites during low-activity periods, separating secure deletion from performance-critical operations to minimize write amplification and maintain storage device performance
3Productivity
If block migration and flexible remapping are used in storage devices, then storage efficiency is improved, but secure deletion reliability is worsened due to stray copies of deleted data
Solution Approach 1:
The patent implements a feedback mechanism where the secure deletion module continuously monitors block migration operations through metadata updates. When blocks are remapped or migrated, the system receives feedback about the new locations and updates its tracking accordingly, ensuring that secure deletion operations target all current copies of data including those moved by block migration
Solution Approach 2:
The patent replaces physical block tracking with metadata-based logical tracking. Instead of physically following block migrations, the system uses file system metadata and allocation tables to logically track block locations. This substitution allows the secure deletion module to identify and erase all copies of deleted data regardless of physical migration, maintaining secure deletion reliability while preserving storage efficiency benefits
Data Source
AI summary
A disk drive or similar storage medium uses a semantic understanding of its associated file system to monitor file metadata and derive block liveness normally only known by the file system. Knowledge of block liveness can be used to improve the disk performance and to create a disk that provides for secure deletion without explicit instructions from the file system.