Storage Device Command Sequence Verification for Data Integrity
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Solution Overview
Problem
Conventional methods for accessing storage devices by host devices of different versions can lead to data destruction and complex internal configurations due to varying access controls, especially when multiple areas are provided in memory cards.
Innovation Solution
A host device and storage device system that uses a command sequence transmission and response mechanism to determine whether access is acceptable, ensuring data integrity by only allowing access when the command sequence is predetermined, thereby simplifying access control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple areas are provided in memory card and access control based on host device is executed, then compatibility between memory cards and host devices is improved, but internal configuration and control of memory card becomes complex
Solution Approach 1:
The patent segments the command set into two distinct categories: initialization commands (ACMD) that modify data and normal commands (CMD) that do not modify data. This segmentation allows the storage device to apply different access control rules to different command types, enabling version-specific initialization while maintaining simple universal access for normal operations.
Solution Approach 2:
The patent implements preliminary version identification through a version discrimination bit in the R2 response before actual data access occurs. This preliminary action allows the host device to determine the storage device's version and select appropriate initialization commands, preventing data destruction while maintaining compatibility without complex runtime access control.
2Adaptability or versatility
If host devices of different versions access the same storage area, then versatility of access is improved, but data destruction occurs due to version incompatibility
Solution Approach 1:
The patent performs preliminary version identification through a version discrimination bit in the R2 response before allowing data-modifying operations. This preliminary check ensures that only hosts with compatible version understanding can execute initialization commands, preventing data destruction while maintaining universal read access.
Solution Approach 2:
The version discrimination bit acts as an intermediary mechanism between hosts of different versions and the storage device. It provides a simple binary indicator that mediates the interaction, allowing the host to determine whether to proceed with initialization or use standard access patterns, thereby ensuring data integrity without complex version negotiation.
3Reliability
If access control is executed based on host device version, then data integrity is improved, but device complexity increases due to multiple access modes
Solution Approach 1:
The patent segments commands into ACMD (initialization) and CMD (normal) categories with distinct access control rules. This segmentation simplifies the access control logic to a simple conditional check: if version mismatch detected, block ACMD but allow CMD. This approach maintains data integrity while avoiding complex multi-mode access control systems.
4Adaptability or versatility
If multiple command sequences are supported for different host versions, then compatibility is improved, but control complexity increases
Solution Approach 1:
The patent segments the command handling logic into two simple paths based on command type: ACMD commands require version verification and may be blocked, while CMD commands are universally accepted. This segmentation reduces control complexity from managing multiple version-specific command sequences to a simple conditional check on command type and version compatibility.
Data Source
AI summary
A host device transmits a command from a command transmission unit (101a) along a predetermined command sequence. A storage device (2) receives the command in a command reception unit (202a). An access determination unit (202c) determines the sequence of the command transmitted from the host device (1) and determines that reception of the access to the host device (1) is enabled only when the sequence is identical with a predetermined sequence. Thus, with simple control, it is possible to prevent data destruction by a host device of an old version.