Backup Data Verification via Client-Side Hashing
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Solution Overview
Problem
Existing backup systems face inefficiencies and inaccuracies in verifying the integrity of backup data, especially in network environments, due to the need to remount multiple backup media and the risk of transmission errors, which can lead to partial backups and unreliable data recovery.
Innovation Solution
A method that uses hash algorithms, such as MD-5, to verify the accuracy of backup data without requiring access to the original source data, by generating and storing hashes during the backup process, allowing for offline verification and reducing the burden of network errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If verification is performed by comparing backup data with original source data, then data integrity can be verified, but the verification process requires remounting all backup media which substantially increases time and overhead burden
Solution Approach 1:
The patent applies preliminary action by computing and storing hash values of the original source data during the backup process itself. This pre-computed hash is stored alongside the backup data, eliminating the need to remount and reread source data during verification. When verification is needed, only the backup media needs to be mounted and its hash compared against the pre-stored hash, dramatically reducing verification time and overhead.
2Reliability
If backup operations are performed during scheduled backup windows, then data redundancy is maintained, but network errors during data transfer can result in invalid backup data
Solution Approach 1:
The patent introduces hash values as an intermediary element that mediates between the backup data and verification process. Instead of directly comparing large volumes of backup data with source data (which is vulnerable to network errors during transfer), the system computes compact hash values during backup and uses these intermediaries for verification. This intermediary approach maintains reliability while being resilient to network errors since the hash comparison requires minimal data transfer.
3Measurement precision
If verification is performed after source data changes between backup and verification, then miscompare errors occur even with correct backup copying
Solution Approach 1:
The patent resolves this contradiction by performing the action of hashing the source data preliminarily during the backup process itself, storing this hash with the backup data. This pre-computed hash serves as a timestamped reference of the source data state at backup time. During verification, this pre-stored hash is compared against a new hash computed from current backup data, allowing accurate verification without requiring the original source data to remain unchanged, thus eliminating miscompare errors.
Data Source
AI summary
A backup method for a computer system network avoids generating hashes from data that may be inaccurate due to network errors affords verification of source data written to backup media includes reading at a network client a portion of the source data from a source storage volume and generating a hash of the source data at the client. The source data and hash are transmitted to a backup server and written to the backup media. The hash is written to the backup media is associated with the backup data corresponding to the source data from which the hash was generated. Verification of the backup data is performed by reading the backup data from the backup media, generating a hash from the backup data read, and comparing that hash with the hash originally stored on the backup media. This enables the backup data to be verified as corresponding to the original source data without the necessity of rereading the source data from the source volume, and enables faster, more accurate off-line verification subsequent to the backup process.