Incremental Backup Descriptor Comparison Bitmap
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Solution Overview
Problem
Conventional incremental backup methods require significant time and resources to identify and archive unchanged data blocks, especially when dealing with large volumes of data, leading to inefficiencies and high costs.
Innovation Solution
A method that selects areas for backup, reads descriptors of logical storage units, compares them with archived units, and uses bit-wise comparison, checksums, or hash functions to determine which physical storage units need archiving, employing a bitmap to mark and archive only necessary units, thereby reducing unnecessary data blocks from the archiving process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If incremental backup is performed on a physical level by comparing data blocks, then the ability to restore system functionality is improved, but the time and CPU resources required for identification and comparison increase significantly
Solution Approach 1:
The patent introduces an intermediary mechanism (bitmap and descriptor comparison) that mediates between the need for physical-level backup reliability and the need to reduce backup time. Instead of directly comparing all data blocks, the system uses descriptors as intermediaries to identify candidate blocks, then uses a bitmap to track and exclude unchanged blocks efficiently.
Solution Approach 2:
The backup process is segmented into multiple stages: first comparing descriptors (metadata) to identify potential changes, then using a bitmap to mark blocks requiring backup, and finally performing selective archiving. This segmentation avoids the need to compare and process every data block in full detail.
2Reliability
If incremental backup is performed on a physical level by comparing data blocks, then comprehensive archiving is achieved, but the CPU resources and computational effort required increase considerably
Solution Approach 1:
The system performs preliminary actions by comparing descriptors (such as file attributes, timestamps, and metadata) before performing full data block comparison. This preliminary filtering identifies only those blocks that may have changed, significantly reducing the scope of subsequent detailed comparison and archiving operations.
Solution Approach 2:
The patent changes the parameters used for comparison from full data block content to descriptor attributes (metadata, timestamps, file information). This parameter transformation reduces the computational complexity from comparing entire data blocks to comparing smaller descriptor structures, thereby reducing CPU resource consumption.
3Measurement precision
If descriptors and data blocks are compared in detail to identify unchanged blocks, then archiving accuracy is improved, but the processing time and system resources increase
Solution Approach 1:
The system performs partial comparison actions by first comparing descriptors (partial information) rather than full data blocks. This partial action is sufficient to identify most unchanged blocks, and the bitmap mechanism ensures that only potentially changed blocks undergo further processing, achieving good enough accuracy without excessive processing time.
Data Source
AI summary
A method of incremental backup of a storage device includes reading descriptors of logical storage units of the storage device; comparing the descriptors of the logical storage units of the storage device with descriptors of archived logical storage units; for logical storage units of the storage device whose descriptors are not identical to the descriptors of the archived logical storage units, backing up contents of physical storage units that correspond to those logical storage units of the storage device; and, for logical storage units of the storage device whose descriptors are identical, performing a comparison step to check if these logical storage units need to be backed up. The logical storage units can be files. The comparison step can be, e.g., (1) bit-wise comparison of the logical blocks, (2) comparing control sums of the logical blocks, and (3) comparing log files relating to the logical storage units The physical storage units can be blocks. The descriptors can be, e.g., MFT entries, hash function values, timestamps, checksums, and file metadata. The descriptors can be compared on a physical storage unit basis. The method further can optionally include generating a bitmap of the physical storage units of the storage device; marking, in the bitmap, those physical storage units that correspond to logical storage units with different descriptors; and archiving content of the physical storage units marked in the bitmap. The method can further optionally include archiving logical storage units of the storage device having the same name as corresponding archived logical storage units of the storage device, but different time stamps.