Storage Controller CDP Restoration Using Sequence Numbers
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Solution Overview
Problem
Continuous data protection (CDP) techniques face challenges in reducing restoration processing time, especially in environments with multiple production volumes, as they require processing numerous journals to restore data to a specific time point, leading to increased processing time.
Innovation Solution
A storage system that includes a storage controller managing a CDP meta volume for history information and a CDP data volume, which searches for relevant history information and uses SEQ numbers to efficiently copy and restore data, focusing on the immediate pre-restoration journal to speed up the restoration process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If all journals are sequentially written to restore data to the recovery point, then complete data restoration is achieved, but restoration time becomes excessively long
Solution Approach 1:
The patent applies partial action by identifying and processing only the necessary subset of journals required for restoration. Instead of sequentially processing all journals from the recovery point to the present, the system determines the specific recovery point and processes only journals relevant to that point, thereby reducing restoration time while maintaining data restoration completeness
Solution Approach 2:
The patent implements preliminary action by pre-managing journal information in a journal management table that tracks SEQ numbers, evacuation times, and volume associations. This pre-organization of journal data allows the restoration process to quickly identify and access only the necessary journals for the target recovery point, eliminating the need to sequentially process all journals
2Adaptability or versatility
If the number of production volumes managed in the CDP group increases, then system capacity and versatility improve, but the number of journals to be processed for restoration increases proportionally
Solution Approach 1:
The patent applies segmentation by organizing journal information into a structured journal management table that separates and indexes journals by volume, SEQ number, and evacuation time. This segmentation allows the restoration process to efficiently query and process only the journals relevant to specific volumes and recovery points, rather than processing all journals across all volumes in the CDP group
Solution Approach 2:
The patent introduces a journal management table as an intermediary structure between the multiple production volumes and the restoration process. This intermediary organizes and indexes journal information, enabling efficient retrieval and processing of only the necessary journals for restoration, thereby reducing the complexity that would otherwise increase proportionally with the number of managed volumes
Data Source
AI summary
A storage controller configures a plurality of logical volumes, a CDP meta volume that manages history information related to writing from a server system for the logical volumes, and a CDP data volume that stores data of the plurality of logical volumes. The storage controller searches for, if a restoration request including a restoration time is received, the restoration request having one of the plurality of volumes as a restoration target volume, history information of the restoration target volume from the CDP meta volume, copies, in a case in which an evacuation time of old data included in the searched history information of the restoration target volume is newer than the restoration time, an SEQ number of the searched history information as first restoration control information, and acquires old history information on the basis of a previous SEQ number of the restoration target volume from the CDP meta volume.