Secondary Storage Controller Data Loss Recovery Mechanism
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Solution Overview
Problem
Current storage systems lack an automated mechanism to restore data lost due to media errors on secondary volumes in peer to peer remote copy (PPRC) systems, requiring manual processes that can be time-consuming, especially for large volumes or multiple affected volumes.
Innovation Solution
A method where the secondary storage controller accumulates information on data loss and transmits it to the primary storage controller, which updates a data structure to facilitate automatic data recovery by resending the lost data tracks, allowing for efficient restoration without changing existing PPRC code.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If manual data restoration processes are used for secondary volumes with media errors, then data can be restored, but the recovery time is excessively long especially for large volumes or multiple affected volumes
Solution Approach 1:
The system performs preliminary actions by maintaining a current data structure at the primary storage controller that reflects the latest state of primary volume tracks. When data loss is detected on the secondary volume, this pre-maintained data structure enables immediate restoration without manual intervention or lengthy recovery procedures, directly resolving the time loss issue while ensuring data reliability.
2Reliability
If the entire volume is restored when data loss occurs on secondary volume, then all data is protected, but processing time is wasted restoring tracks that have not lost data
Solution Approach 1:
The restoration process is segmented by using track information from the current data structure to identify and restore only the specific tracks that have suffered data loss, rather than restoring the entire volume. This segmentation approach maintains complete data protection for affected tracks while significantly improving restoration efficiency by avoiding unnecessary processing of intact tracks.
Solution Approach 2:
The system applies local quality by treating different tracks differently based on their actual data loss status. Tracks with data loss are restored using information from the current data structure, while tracks without data loss are left unchanged. This localized approach ensures complete protection where needed while maximizing restoration efficiency where not needed.
3Reliability
If frequent interruptions are sent to primary storage controller for data loss reporting, then data loss information is captured promptly, but processing time is lost due to repeated interruptions
Solution Approach 1:
The secondary storage controller performs preliminary accumulation of data loss information across multiple interruptions before transmitting to the primary storage controller. This preliminary action reduces the frequency of communications while ensuring all data loss instances are captured, thereby maintaining detection accuracy while minimizing processing time loss from repeated interruptions.
Solution Approach 2:
Instead of immediate transmission for each data loss event, the system implements periodic accumulation of data loss information followed by batch transmission. This periodic approach maintains reliable detection of all data loss events while significantly reducing the overhead of frequent interruptions and processing time.
Data Source
AI summary
A secondary storage controller determines one or more tracks of one or more volumes in which data loss has occurred in the secondary storage controller. The secondary storage controller suspends a peer to peer remote copy operation between the secondary storage controller and a primary storage controller. Information on the one or more tracks of the one or more volumes in which the data loss has occurred is transmitted to the primary storage controller.