Backup Method for Hierarchical Storage Systems
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Solution Overview
Problem
The increasing volume of 'big data' leads to prolonged restoration times in file system recovery, as existing backup methods require reading all backup data from tapes, making it difficult to resume operations quickly during disasters.
Innovation Solution
A backup method that simultaneously backs up metadata and index data, allowing for rapid restoration by managing hierarchical storage across multiple media, enabling the file system to operate even during the backup process and improving storage media efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If all backup data is read out from tapes for restoration, then complete data recovery is achieved, but restoration time becomes extremely long
Solution Approach 1:
The backup data is segmented into two distinct parts: metadata (file system structure, directory information, file attributes) and actual data content. The metadata is backed up separately and can be restored independently to a different system, enabling immediate file system reconstruction without waiting for complete data transfer from tapes.
Solution Approach 2:
The metadata is backed up in advance and stored separately from the main data tapes. This preliminary backup of structural information allows the file system to be reconstructed quickly at the start of restoration, before the time-consuming process of reading all data from tapes begins.
2Loss of energy
If backup data is saved on tapes while data is retained on disk, then storage cost is reduced, but work cannot be resumed until all data is read from tapes
Solution Approach 1:
The system segments backup operations into metadata backup and data backup. Metadata is backed up to fast storage media, enabling quick restoration of file system structure and immediate resumption of work, while data continues to be transferred from tapes in the background without blocking productivity.
Solution Approach 2:
A metadata backup serves as an intermediary that enables file system reconstruction without requiring complete data transfer from tapes. This intermediary structure allows the system to become operational with placeholder references to data locations, which are then populated as data is read from tapes.
3Reliability
If metadata and index are backed up simultaneously, then restoration consistency is improved, but backup complexity increases
Solution Approach 1:
The backup processes for metadata and index are merged into a coordinated simultaneous operation. Both data structures are captured at the same point in time, ensuring consistency between them during restoration without requiring separate backup sequences or complex synchronization logic.
Data Source
AI summary
A backup method is provided for a file system for managing hierarchical storage including one or more storage media on a computer system including one or more computers. Each of the one or more storage media includes a data part which is separated from an index and on which updated information is appended and kept. Each of a plurality of pieces of data within the file system is managed to be migrated to at least any of the one or more storage media. The backup method includes backing up metadata of the plurality of pieces of data migrated within the file system; and backing up the index of each of the one or more storage media to which the plurality of pieces of data have been migrated, substantially at the same time point as the metadata.