Job Execution Device Storage Area Management for Data Deletion
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Solution Overview
Problem
Existing data deletion methods, such as those described in Japanese Patent Application Publication No. 2008-42805, face issues where the overwrite deletion process is interrupted, leading to inefficiencies in using storage resources, as clusters requiring overwrite deletion are not released promptly, causing a shortage of available storage areas for new data.
Innovation Solution
A job execution device that manages storage areas by using a file system with a file allocation table and a management table to prioritize overwrite deletion for clusters based on necessity and usage frequency, allowing for the interruption of overwrite deletion during job execution and restarting it when necessary, ensuring that storage resources are efficiently utilized.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the overwrite deletion process is executed sequentially for clusters requiring deletion, then data security is improved, but storage resource utilization deteriorates because clusters are occupied until deletion completes
Solution Approach 1:
The patent segments the overwrite deletion process into individual cluster-level operations rather than treating it as a bulk operation. Each cluster's deletion status is independently tracked in the management table, allowing the system to manage and release clusters individually as deletion completes, thereby improving storage resource utilization while maintaining data security.
Solution Approach 2:
The patent performs preliminary actions by updating the management table to mark clusters as requiring overwrite deletion immediately when deletion is requested, before the actual overwrite operation begins. This allows the file system to recognize and release these clusters for new data allocation while the overwrite deletion executes in the background, resolving the contradiction between security and resource utilization.
2Productivity
If the file system changes cluster status to unused before overwrite deletion completes, then storage availability is improved, but data security deteriorates because new data may be written to clusters still containing sensitive information
Solution Approach 1:
The patent introduces the management table as an intermediary layer between the file system and the actual data on storage media. This management table tracks which clusters require overwrite deletion separately from their allocation status, allowing the file system to release clusters for new data while the overwrite deletion process continues independently, thus maintaining both security and availability.
Solution Approach 2:
The patent implements dynamic status management where clusters can transition between different states (in use, unused, requiring overwrite deletion) independently. The management table is dynamically updated to reflect the current state of each cluster, allowing flexible resource allocation while ensuring that overwrite deletion operations are properly tracked and completed for security-critical clusters.
3Speed
If the overwrite deletion is interrupted during job execution, then job processing speed is improved, but deletion completeness deteriorates
Solution Approach 1:
The patent implements periodic action by allowing the overwrite deletion process to be interrupted and resumed multiple times. The management table maintains the state of which clusters have been processed, enabling the system to pause deletion during high-priority job execution and resume it later, ensuring eventual completion while maintaining job processing flexibility and speed.
Data Source
AI summary
A job execution device includes: a storing unit; a file system that divides a storing area of the storing unit into a plurality of division areas, and manages the storing area of the storing unit; a management table in which deletion management information indicating whether an overwrite deletion is necessary is registered for each of the division areas; a deletion processing unit; a job execution unit; and a management table updating unit. When the file system receives the releasing request, the file system changes the division area management information for the division areas to be released by the releasing request so as to change the status to “unused” before the deletion management information for all of the division areas to be released by the releasing request is changed to a non-necessity of the overwrite deletion.