Incremental Backup Hard Links via Inode Change Logs
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Solution Overview
Problem
Existing backup systems face performance degradation and resource wastage due to the need to process unnecessary disk accesses and frequent full backups caused by conventional change logs, especially in large file systems with high change rates, and the challenge of efficiently tracking hardlinks during incremental backups.
Innovation Solution
The implementation of a system that uses a change log with unique identifiers, such as inode numbers, to index file changes, and efficiently manages hardlinks by creating new and deleted file name lists to avoid unnecessary disk accesses and limit the change log size, allowing for incremental backups based on these lists.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional change log records every change in temporal order for all files, then complete file change history is maintained, but backup performance degrades due to processing unnecessary disk accesses and the change log size becomes unmanageably large
Solution Approach 1:
The patent segments the change log processing by file type, separating hardlinks from regular files. Hardlinks are tracked using an inode-based mechanism that groups multiple filenames pointing to the same data, while regular files use traditional change log records. This segmentation allows the system to process only relevant changes during backup operations, eliminating unnecessary disk accesses for deleted files while maintaining complete change history.
Solution Approach 2:
The patent introduces an intermediary inode-based tracking mechanism that sits between the file system and the change log. Instead of directly recording every file change in temporal order, the system uses inodes as intermediaries to aggregate hardlink information and determine which files actually need backup. This intermediary layer filters out redundant change log records while preserving the complete history of file modifications.
2Reliability
If the change log grows to record all file changes over time, then complete backup history is maintained, but the change log size becomes too large requiring frequent purging or wrapping
Solution Approach 1:
The patent segments change log management by file type, maintaining separate tracking mechanisms for hardlinks (using inodes) and regular files. This segmentation prevents the change log from growing indefinitely by only recording relevant changes and using compact inode-based storage for hardlink information, reducing the overall volume of stored data while preserving complete backup history.
Solution Approach 2:
The patent changes the parameter of change log storage by transitioning from temporal ordering of all file changes to an inode-based indexing system. This parameter change allows the system to store change information in a more compact form, grouping related changes by inode and eliminating redundant records, thereby maintaining complete backup history with reduced storage requirements.
3Measurement precision
If a backup application trawls the entire file system to generate a list of changed files, then all changed files are identified, but significant computing resources are consumed
Solution Approach 1:
The patent introduces an intermediary change log and inode tracking mechanism that pre-processes and organizes file change information. Instead of trawling the entire file system during backup operations, the system queries the pre-populated change log and inode structures to identify changed files. This intermediary mechanism maintains precise identification of changed files while dramatically reducing computing resource consumption during backup execution.
4Loss of time
If incremental backups are performed using conventional change logs, then backup time is reduced, but performance degrades due to processing unnecessary disk accesses for deleted files
Solution Approach 1:
The patent segments the incremental backup process by file type, using inode-based tracking for hardlinks to determine which files actually exist and need to be backed up. This segmentation eliminates the processing of unnecessary disk accesses for deleted files that plague conventional change log approaches, maintaining short backup times while preserving backup performance through targeted file selection.
Data Source
AI summary
Incrementally backing up file system hard links based on change logs is described. A system identifies a unique identifier and a file name associated with a file event in a file system. The system determines whether a change log for the file system lacks an association between the unique identifier and the file name. The system adds the file name to one of a new file name list and a deleted file name list associated with the change log in response to a determination that the change log for the file system lacks the association between the unique identifier and the file name. The system incrementally backs up the file event based on at least one of the new file name list and the deleted file name list.