Read Request Manager Redirects Requests During Protected Restore
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
During protected restore operations in data storage systems, the processing of read requests can lead to significant degradation in host read performance due to queuing, as the number of queued read requests increases, resulting in unacceptably long times to process read requests during prolonged restore operations.
Innovation Solution
Implement a method to redirect read requests to the clone instead of queuing them, using a read request manager that determines whether to redirect the request based on a delta map and protected restore map, allowing read requests to be processed from the clone if the data has not yet been copied back to the source, thereby avoiding the delay associated with queuing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If read requests are queued during a protected restore operation, then data integrity is maintained, but read performance degrades significantly
Solution Approach 1:
The patent segments read requests into two categories: those that can be served from the source volume and those that must be queued. By dividing the read request processing path, the system maintains data integrity for critical reads while allowing non-critical reads to proceed without queuing, thus preserving both reliability and performance
Solution Approach 2:
The patent applies different processing qualities to different read requests based on their characteristics and the state of the restore operation. Critical read requests that require data consistency are queued, while non-critical reads are served immediately from the source, creating local quality variations in processing strictness
2Productivity
If read requests are served immediately from the source during protected restore, then read performance is maintained, but data consistency is compromised
Solution Approach 1:
The patent performs preliminary actions by pre-identifying which read requests can be safely served from the source volume before the restore operation completes. Using metadata about the restore state, the system determines in advance which reads will return consistent data, allowing immediate servicing without compromising data consistency
3Reliability
If the protected restore operation is allowed to proceed without intervention, then data restoration is ensured, but host read access time increases
Solution Approach 1:
The patent introduces an intermediary component that sits between the host and the storage system during protected restore operations. This intermediary intercepts read requests, determines their eligibility for immediate servicing based on restore state metadata, and either serves them directly or queues them appropriately, thus mediating between restoration requirements and access performance
Data Source
AI summary
According to one aspect, the subject matter described herein includes a method for processing read requests received during a restore operation, where a protected restore operation includes copying at least a portion of the data content of the clone to its source. The method includes receiving a read request to read data from a source during a protected restore operation. It is determined whether to redirect the read request to the clone, and in response to determining to redirect the read request to the clone, the read request is redirected to read data from the clone.