Orphan Block Recovery via Replication in File Systems
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Solution Overview
Problem
Traditional file systems face inefficiencies and user experience issues when detecting orphan storage blocks, as they require offline recovery, leading to data unavailability and reduced storage management efficiency.
Innovation Solution
A method that identifies orphan storage blocks during file system recycling, replicates their data to a target storage block within an isolation area, and generates metadata to maintain data integrity and accessibility, allowing continuous recycling operations without data loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the file system goes offline to remove orphan storage blocks, then data integrity is maintained, but data availability deteriorates and user experience is severely affected
Solution Approach 1:
The patent applies preliminary action by creating a snapshot of the file system state before recycling operations. This snapshot captures the mapping between storage slices and storage blocks, allowing the system to identify and handle orphan blocks without going offline. The snapshot is created in advance and used to guide the recycling process, ensuring data integrity while maintaining availability.
Solution Approach 2:
The patent introduces a snapshot as an intermediary structure that mediates between the recycling operation and the file system. The snapshot stores the pre-recycling mapping information and acts as a reference during the recycling process, enabling the system to safely remove orphan blocks without affecting client access to valid data.
2Reliability
If the file system goes offline to detect and remove orphan storage blocks, then storage management correctness is improved, but storage management efficiency deteriorates
Solution Approach 1:
The system performs preliminary actions by creating a snapshot of the storage slice to block mapping relationships before recycling begins. This pre-captured information enables the recycling process to efficiently identify orphan blocks without interrupting file system operations, thereby maintaining both correctness and efficiency.
Solution Approach 2:
The patent uses copying by creating a snapshot copy of the storage mapping information. This copy is used during recycling to identify orphan blocks, allowing the original file system structures to remain intact and accessible while the recycling operation proceeds independently and efficiently.
3Quantity of substance
If orphan storage blocks are removed from the file system, then storage space is recovered, but data loss occurs
Solution Approach 1:
The patent applies preliminary action by creating a snapshot that records the mapping between storage slices and storage blocks before recycling. This snapshot is used to identify which blocks are truly orphaned (not referenced by any valid file) versus which blocks contain valid data. Only confirmed orphan blocks are removed, preventing data loss while recovering storage space.
Solution Approach 2:
The system uses feedback by continuously referencing the snapshot during the recycling process to verify whether each storage block is an orphan. The snapshot provides the ground truth mapping information, and the recycling operation adjusts its actions based on this feedback, ensuring that only blocks with no valid references are removed.
Data Source
AI summary
Techniques for storage management involve: if it is determined that a source storage slice of a file system is to be recycled, identifying, from the source storage slice including a plurality of storage blocks, an orphan storage block that is inaccessible by a client of the file system; replicating data of the orphan storage block to a target storage block, the target storage block being located in a target storage slice within a predetermined isolation area of the file system; and generating second metadata of the target storage block based at least on first metadata of the orphan storage block, the second metadata including at least an identification of the orphan storage block. Therefore, the management performance can be improved, and the storage costs can be reduced.