File System Point-in-Time Recovery via Journal Undo Operations
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Solution Overview
Problem
Continuous data protection methods, such as RecoverPoint, primarily support storage volumes and do not natively provide point-in-time recovery for file systems, as they operate using different access protocols and semantics compared to volumes.
Innovation Solution
An improved technique for continuous data protection and point-in-time recovery for file systems involves writing changes to a journal and undoing identified changes to restore the file system to a previous state, allowing for replication and recovery of file systems and Virtualized Storage Processors (VSPs) as a single unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If continuous data protection is implemented using volume-based replication protocols (Fibre Channel, iSCSI), then reliable point-in-time recovery is achieved for storage volumes, but file systems cannot be recovered because they use different access protocols (NFS, CIFS, SMB) and semantics
Solution Approach 1:
The patent introduces an intermediary layer that translates file system operations into volume-based replication operations. The file system changes are captured, converted into a format compatible with existing volume replication protocols, and then replicated to the destination. This mediator enables file system protection without requiring new protocols, resolving the contradiction between reliability and adaptability.
Solution Approach 2:
The patent segments the file system protection functionality into distinct components: a file system monitor that captures changes, a translation layer that converts operations, and the existing replication infrastructure. This segmentation allows the system to leverage proven volume replication technology while adding file system support, achieving both reliability and protocol versatility.
2Adaptability or versatility
If file system changes are replicated by converting to volume-based operations, then continuous data protection is extended to file systems, but the complexity of the replication system increases due to protocol translation requirements
Solution Approach 1:
The patent creates a universal replication interface that can handle multiple file system types and protocols through a common translation mechanism. This multi-functional approach consolidates what would otherwise require separate replication systems for each file system type, reducing overall system complexity while maintaining broad adaptability.
3Stability of the object's composition
If multiple file systems are grouped into a VSP for unified replication, then consistent point-in-time recovery across multiple file systems is achieved, but the management complexity of individual file systems increases
Solution Approach 1:
The patent merges multiple file systems into a unified VSP object for replication purposes. This combining approach maintains the individual integrity and manageability of each file system while providing consistent protection and recovery across the entire group. The VSP acts as a container that preserves individual file system characteristics while enabling coordinated operations.
Data Source
AI summary
A technique for performing continuous data protection and point-in-time recovery for file systems includes performing continuous replication to maintain a replica of a file system by writing changes in the file system to a journal and then writing the changes from the journal to the replica. In response to receiving a request to roll back the replica to a previous point in time, the technique accesses the journal to identify changes made to the replica since the previous point in time and performs undo operations to undo the identified changes and restore the replica to its state at the previous point in time.