Serializing Replication Operations for Storage Consistency
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Solution Overview
Problem
Synchronous replication systems face challenges in handling misaligned holes and writes beyond the end of files, leading to data divergence and inconsistencies between primary and replica storage objects, which can disrupt the zero recovery point objective (RPO) and cause replication errors.
Innovation Solution
The system dynamically allocates and recycles file range locks to maintain the order of overlapping writes, uses an overlapping write manager to serialize writes, and performs a quick reconcile operation to handle misaligned holes and writes beyond the end of files by aligning offsets and executing truncate commands to ensure data consistency between storage objects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If synchronous replication is implemented to ensure data consistency and zero RPO, then data protection reliability is improved, but system complexity increases due to the need to handle misaligned holes and writes beyond end of files
Solution Approach 1:
The replication process is segmented into distinct phases: primary operation execution on the first storage object, followed by separate handling of special cases (misaligned holes and writes beyond end of file) during the quick reconcile phase. This segmentation allows the system to maintain synchronous replication reliability while managing complexity through structured problem decomposition.
Solution Approach 2:
The system performs preliminary validation and alignment checks before executing the quick reconcile operation. By preparing the replication state in advance and identifying potential misalignment issues before they cause problems, the system maintains data consistency without requiring complex real-time handling mechanisms.
2Reliability
If quick reconcile operation is performed to handle misaligned holes and writes, then data consistency is improved, but processing time increases
Solution Approach 1:
The quick reconcile operation skips directly to handling only the specific misaligned cases (holes and writes beyond end of file) rather than performing a complete reconciliation of all data. This targeted approach maintains data consistency while minimizing the time penalty by focusing computational resources only on problematic areas.
Solution Approach 2:
The system changes the operational parameters during quick reconcile by adjusting offset alignments and truncating files to match the primary storage object state. These parameter adjustments resolve consistency issues efficiently by transforming misaligned data structures into aligned ones without requiring extensive data movement or processing.
3Manufacturing precision
If file range locks are dynamically allocated and recycles to maintain write order, then manufacturing precision of replication is improved, but device complexity increases
Solution Approach 1:
File range locks are dynamically allocated when needed to maintain write order during replication and then recovered (released) when no longer required. This on-demand lock management approach ensures replication precision by maintaining proper ordering when necessary, while reducing overall system complexity by not holding locks permanently or allocating them for all operations.
Data Source
AI summary
Techniques are provided for serializing replication operations. A plurality of operations are implemented upon a first storage object and are replicated as a plurality of replication operations. An order with which the plurality of replication operation are to be executed upon a second storage object is determined. Execution of the plurality of replication operations upon the second storage object is serialized according to the order.