Dynamic Chunk Allocation Backup Void Data Detection
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Solution Overview
Problem
Conventional storage systems with dynamic chunk allocation (DCA) capability face issues with waste storage chunks during backup and restore operations, as they allocate physical blocks even in unused segments, leading to unnecessary storage space allocation and waste.
Innovation Solution
The method involves a system with a chunk table import/export program, a mode select program, and a void data detecting step to avoid allocating chunks in unused segments during backup and restore, ensuring only allocated data is written back, thus preventing unnecessary allocation and waste.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional backup techniques are applied to DCA volumes, then the backup process reads the volume from beginning to end, but physical storage space is allocated to segments that have not yet received write commands, resulting in wasted physical blocks
Solution Approach 1:
The patent extracts and backs up only the allocated chunks (segments with actual data) from the DCA volume, rather than backing up the entire volume including unallocated segments. This is achieved by modifying the backup process to identify and backup only those segments that have received write commands and have physical storage allocated, thereby preventing waste of physical blocks during restore operations
Solution Approach 2:
The patent performs preliminary identification of allocated chunks before the backup process begins. By maintaining metadata that tracks which segments have physical storage allocated, the system can pre-determine the exact scope of data to be backed up, avoiding unnecessary backup of unallocated segments and subsequent waste during restore
2Reliability
If the backup computer restores the whole backup image to the DCA storage system, then data recovery is achieved, but write commands are issued to all allocated address blocks causing unnecessary chunk allocation and storage waste
Solution Approach 1:
The restore process extracts and restores only the allocated chunks that were originally backed up, rather than restoring the entire volume image. The system uses metadata to identify which segments contain actual data and restores only those segments to the DCA storage system, preventing unnecessary chunk allocation for unallocated segments
Solution Approach 2:
The patent performs preliminary identification of which chunks need to be restored by examining the backup metadata before the actual restore operation begins. This allows the system to pre-determine the exact scope of restoration needed, avoiding unnecessary write commands and chunk allocation for segments that were never allocated in the first place
3Productivity
If a large volume is thin-provisioned with only a small percentage of capacity allocated to physical storage areas, then storage efficiency is improved, but conventional backup creates large backup images containing mostly default void data pattern
Solution Approach 1:
The backup process extracts and backs up only the allocated chunks that contain actual data, excluding the large portions of the volume that have not yet received write commands. By using metadata to identify allocated segments, the system creates compact backup images containing only the necessary data, dramatically reducing backup image size for thin-provisioned volumes
Solution Approach 2:
The patent performs preliminary analysis of the volume's allocation status before beginning the backup process. By examining metadata that tracks which segments have physical storage allocated, the system can pre-calculate the exact size and scope of the backup needed, avoiding creation of large backup images filled with default void data patterns
Data Source
AI summary
Backup and restore operations are made possible in a storage system that has dynamic chunk allocation (DCA) capability. In a DCA storage system, a chunk of physical storage area is not allocated to a segment of a volume until a write command is received targeting the segment of the volume. During a restore operation of the volume in the DCA storage system, the wasting of storage capacity when a backup image of the volume is restored is mitigated by preventing allocation of physical storage areas to segments of restore data that are only void data.