Storage System Time-Tag Coordination for Nonblocking Snapshots
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Solution Overview
Problem
Existing data backup methods, such as snapshots, cause significant performance fluctuations due to blocking I/O operations to ensure data consistency, which is unacceptable for critical systems requiring continuous service.
Innovation Solution
A data write method and storage system that ensures time consistency during snapshot operations by using controllers to manage time tags and maintain correspondence between data write requests and time tags, reducing performance fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If I/O operations are blocked to ensure data consistency during snapshot operations, then data consistency is improved, but system performance deteriorates due to performance fluctuations and increased downtime
Solution Approach 1:
The patent segments the snapshot operation into two phases: a preparation phase where the time tag is updated and propagated to all controllers, and an execution phase where I/O operations are processed with the new time tag. This segmentation allows data consistency to be ensured through coordinated time tag management while avoiding the need to block all I/O operations simultaneously, thus reducing performance impact.
Solution Approach 2:
The patent applies preliminary action by updating the time tag and broadcasting this change to all controllers before actually performing the snapshot operation. This preparation ensures that all controllers are synchronized and ready to process I/O operations with the correct time tag, eliminating the need to block I/O operations during the snapshot process itself.
2Reliability
If I/O operations are blocked during snapshot operations, then data consistency is ensured, but the backup window increases causing unacceptable downtime for critical systems
Solution Approach 1:
The patent divides the snapshot process into a coordination phase (updating time tags and broadcasting to controllers) and an execution phase (processing I/O operations). This segmentation ensures that data consistency is established through time tag coordination before I/O processing begins, eliminating the need to block I/O operations during the snapshot process and thus reducing the backup window.
Solution Approach 2:
The patent enables continuous processing of I/O operations by maintaining the ability to process requests with the new time tag without blocking. The system continuously updates time tags and propagates changes to controllers, allowing I/O operations to continue uninterrupted while ensuring data consistency through coordinated time tag management across all controllers.
Data Source
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AI summary
The invention discloses a data write method applied to a storage system. The storage system includes a first controller and a second controller, and the method includes: after receiving a first data write request, determining, by the second controller, whether a locally stored first time tag is in an expired state; when determining that the locally stored first time tag is in the expired state, reading, by the second controller, the first time tag from the first controller; and storing, by the second controller, a correspondence between the first time tag and the first data write request. Embodiments of the present invention ensure time consistency when a snapshot operation is performed on a logical storage area, and reduce performance fluctuation.