Stub File Retention Coordination in Hierarchical Storage

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Solution Overview

Problem

In hierarchical storage systems, there is a need to protect both primary and secondary storage files for retention periods, ensuring that stub files in primary storage are retained and coordinated with the retention protection of secondary storage to comply with regulatory requirements such as SEC Rule 17a-4 and Sarbanes-Oxley Act, while maintaining data authenticity and preventing changes to files before the retention period expires.

Innovation Solution

A computer-implemented method and system where the primary file server replaces files with stub files in primary storage, setting attributes to indicate retention periods, and the secondary file server retains data for the specified period, with the primary server rejecting requests to change the stub files until the retention period expires, ensuring coordinated retention protection across both storage types.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If files are migrated from primary storage to secondary storage and replaced with stub files, then storage capacity is optimized and access efficiency is maintained, but retention protection coordination between primary and secondary storage becomes complex

Engineering Contradiction:

Improvestorage capacity optimizationVSAvoidretention protection coordination

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent merges retention protection functionality into the stub file metadata structure. The stub file contains both the reference to the secondary storage location and the retention period information, combining what were previously separate concerns (file location tracking and retention management) into a single integrated structure. This allows the primary file server to enforce retention policies on stub files using the same mechanisms it uses for regular files, without requiring separate coordination systems.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The stub file acts as an intermediary that bridges primary and secondary storage systems. It contains metadata about the migrated file including its location in secondary storage and the retention period. This intermediary structure allows the primary file server to maintain retention control without direct involvement from the secondary storage system, simplifying the coordination between the two storage tiers.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If stub files are protected with retention periods, then data authenticity is maintained and regulatory compliance is achieved, but file modification flexibility is reduced

Engineering Contradiction:

Improvedata authenticityVSAvoidfile modification flexibility

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The retention protection applied to stub files is dynamic and time-based. The stub file attribute indicates a retention period, and the file is protected from modification only during this period. Once the retention period expires, the stub file can be modified or deleted normally. This dynamic approach allows the system to maintain data authenticity when required by regulations while automatically restoring flexibility when the retention requirement no longer applies.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system performs preliminary action by setting the retention period on the stub file at the time of migration to secondary storage. This preliminary designation of the retention period allows the system to automatically enforce protection during the required period without requiring ongoing intervention, and then automatically lift the restriction when the period expires, balancing protection with eventual flexibility.

Inventive Principle:

Principle #10Preliminary action

3Reliability

If retention periods are enforced on both primary and secondary storage, then regulatory compliance is ensured, but system operation complexity increases

Engineering Contradiction:

Improveregulatory complianceVSAvoidsystem operation

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts the retention period information from the secondary storage system and embeds it directly in the stub file metadata on the primary storage system. Instead of requiring the primary file server to query or coordinate with the secondary storage system to determine retention status, the retention period is extracted and stored locally in the stub file. This allows the primary file server to enforce retention policies independently, significantly simplifying system operation while ensuring compliance.

Inventive Principle:

Principle #2Taking out (Extraction)

Data Source

PatentUS8170985B2Primary stub file retention and secondary retention coordination in a hierarchical storage system

Publication Date: 2012.05.01 EMC IP HLDG CO LLC

AI summary

A protected file is retained in secondary storage for a retention period, and a corresponding stub file is retained in primary storage for the retention period. The stub file retains attributes of the file indicating a location of the file data in the secondary storage and indicting that the stub file is to be retained for the retention period. A system administrator may instruct a primary file server that a secondary file server supports retention based protection and it is desired to protect stub files corresponding to protected files that are migrated to the secondary file server. The primary file server may request the secondary file server to return a protection status of the file after migration. This enables automatic policy-based migration to both file level retention (FLR) and non-FLR retention protected secondary storage from diverse applications accessing FLR or non-FLR files in the primary storage.