Temporary VTOC Locking During Storage Volume Defragmentation
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Solution Overview
Problem
Current defragmentation operations in computing storage environments lock the volume table of contents (VTOC) for extended periods, disrupting access and causing inefficiencies, especially in high-use production volumes and large extended addressable volumes, as they require multiple passes and prevent data set extensions or allocations during the process.
Innovation Solution
The method involves serializing the VTOC for a volume scan, allocating dummy data sets to reserve target areas, releasing the VTOC serialization to allow I/O operations, and updating the VTOC with actual data after moves are completed, enabling continuous access and allocation during defragmentation, with additional dummy sets created if fragmentation levels remain high.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the VTOC is locked for the duration of the DEFRAG operation, then the defragmentation can be completed without interference, but access to data sets and volume operations are prevented causing disruption on high-use production volumes
Solution Approach 1:
The patent segments the defragmentation process into distinct phases: analysis phase where VTOC is serialized to identify fragmented data sets, and execution phase where dummy data sets are allocated and data is moved. This segmentation allows the VTOC to be released between phases, enabling volume access during parts of the operation while maintaining defragmentation reliability.
Solution Approach 2:
The patent performs preliminary allocation of dummy data sets before actual data movement begins. These dummy data sets reserve the target space needed for defragmentation operations. By preparing this space in advance, the system can proceed with data movement without requiring continuous VTOC serialization, thus allowing volume access during the process.
2Manufacturing precision
If multiple passes are required to defragment a volume, then thorough defragmentation is achieved, but the VTOC remains locked for extended periods increasing disruption
Solution Approach 1:
The patent implements periodic action by releasing the VTOC serialization between multiple defragmentation passes. Instead of maintaining continuous lock, the system performs analysis in periodic intervals with VTOC releases in between, allowing both thorough multi-pass defragmentation and reduced lock duration that minimizes disruption to production volumes.
3Measurement precision
If the VTOC is serialized continuously during DEFRAG, then data set moves can be tracked accurately, but new allocations and data set extends are prevented
Solution Approach 1:
The patent introduces dummy data sets as intermediaries to track data set moves during defragmentation. These dummy data sets serve as placeholders that reserve target space and track movement without requiring continuous VTOC serialization. This intermediary mechanism maintains measurement precision for tracking while allowing the VTOC to be released, thereby restoring allocation flexibility for new data sets and extends.
Data Source
AI summary
Various embodiments for defragmentation of a storage volume in a computing storage environment by a processor device are provided. A volume table of contents (VTOC) is serialized for a volume scan operation. At least one dummy data set in the storage volume is allocated, to be subsequently filled with actual data pursuant to a degragmentation operation. Input/output (I/O) operations are allowed to occur.