Reducing Storage Appliance Aggregate Capacity via Data Relocation
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Solution Overview
Problem
Current storage systems lack the ability to reduce the provisioned storage capacity of a disk or aggregate while maintaining service to clients, with major cloud providers not supporting disk shrinkage, leading to potential waste of storage space.
Innovation Solution
The system identifies a shrink region within the aggregate, relocates valid data to other disks, and removes the source disk to reduce the provisioned storage capacity, utilizing existing data relocation and mirroring technologies to ensure continuous service.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If storage capacity is reduced by removing a disk from the aggregate, then storage space waste is reduced, but service continuity is compromised
Solution Approach 1:
The system performs preliminary data relocation before disk removal by identifying valid data blocks on the source disk and relocating them to destination disks. This preliminary action ensures that when the source disk is removed, all data has already been safely transferred, maintaining service continuity while enabling storage capacity reduction.
Solution Approach 2:
The system introduces destination disks as intermediaries to facilitate data transfer from the source disk. These destination disks act as temporary holding points that enable the source disk to be removed without interrupting service, as data can be redirected to the intermediary destination disks during the transition.
2Productivity
If disk removal is performed while storage appliance is online, then storage utilization is optimized, but data relocation complexity increases
Solution Approach 1:
The system segments the data relocation process into discrete manageable steps: identifying valid data blocks, selecting destination disks, relocating data blocks individually or in batches, and finally removing the source disk. This segmentation reduces overall complexity by breaking down the complex operation into simpler, controllable phases that can be executed while the storage appliance remains online.
Solution Approach 2:
The system implements feedback mechanisms to monitor data relocation progress and validate data integrity during the process. By continuously checking relocation status and data correctness, the system can adjust its operations dynamically, reducing complexity through real-time adjustments and ensuring successful completion while maintaining online service.
3Loss of energy
If provisioned storage capacity is reduced, then costs are minimized, but storage space management complexity increases
Solution Approach 1:
The system performs self-service storage capacity management by automatically identifying disks suitable for removal, selecting optimal destination disks for data relocation, and executing the relocation process without manual intervention. This automation reduces management complexity while enabling cost optimization through proactive storage capacity adjustment based on actual usage patterns.
Solution Approach 2:
The system changes key parameters such as aggregate capacity, disk configuration, and data distribution patterns to reduce storage capacity. By monitoring storage utilization metrics and triggering capacity reduction when appropriate, the system optimizes costs while managing complexity through parameter-driven automated decision-making rather than manual configuration.
Data Source
AI summary
Systems and methods for reducing the provisioned storage capacity of a disk or aggregate of disks of a storage appliance while the storage appliance continues to serve clients are provided. According to one embodiment, the size of the aggregate may be reduced by shrinking the file system of the storage appliance and removing a selected disk from the aggregate. When an identified shrink region includes the entire addressable PVBN space of the selected disk, the file system may be shrunk by relocating valid data from the selected disk elsewhere within the aggregate. After the valid data is relocated, the selected disk may be removed from the aggregate, thereby reducing the provisioned storage capacity of the aggregate by the size of the selected disk.