Selective Erasure of Ephemeral Data in SSDs
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Solution Overview
Problem
Conventional SSDs lack a method for selective erasure of data, particularly ephemeral data, which remains intact until garbage collection, posing security risks due to the inability to erase specific logical addresses or ranges, leading to indeterminate retention of outdated information.
Innovation Solution
Implementing a system and method for SSDs that allows selective erasure of data by modifying the logical to physical mapping table to identify and mark invalid pages, enabling erasure of specific logical addresses or ranges, including ephemeral data, through a selective erase command, using a separate mapping table or metadata to track validity status.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional erase functions are used to delete data for security reasons, then data security is improved, but the entire drive or volume must be erased, causing loss of other valid data
Solution Approach 1:
The patent segments the erase operation to target only specific logical addresses or ranges rather than erasing the entire drive. The controller identifies and erases only the blocks containing the specified logical addresses, leaving other valid data intact. This segmentation resolves the contradiction by enabling selective data deletion for security purposes without affecting unrelated valid data.
2Productivity
If garbage collection is used to erase ephemeral data, then storage space is reclaimed, but ephemeral data remains intact until collection occurs, creating security vulnerability
Solution Approach 1:
The patent implements preliminary action by providing an immediate selective erase function that deletes ephemeral data right when it is no longer needed, rather than waiting for garbage collection. When the controller receives a selective erase command for a logical address, it immediately identifies and erases the corresponding blocks containing ephemeral data, eliminating the security vulnerability window before garbage collection occurs.
3Measurement precision
If selective erasure of specific logical addresses is implemented, then data security and precision are improved, but controller complexity increases due to additional mapping tracking requirements
Solution Approach 1:
The patent applies self-service by utilizing the existing logical-to-physical mapping table that the controller already maintains for normal SSD operations. The selective erase function leverages this existing mapping infrastructure to identify blocks containing specified logical addresses, rather than requiring a completely new tracking system. This approach enables precise selective erasure while minimizing additional controller complexity by reusing existing data structures.
Data Source
AI summary
Various implementations described herein relate to systems and methods for managing selective erasure in a Solid-State Drive (SSD) including receiving a selective erase command corresponding to erasing valid and invalid data mapped to a logical address and in response to receiving the selective erase command, erasing blocks in which one or more pages mapped to the logical address are located based on a mapping table that maps the logical address to the one or more pages. Both valid data and invalid data may be physically stored in one or more pages.