Storage Failover Resynchronization via Operable Volume Segmentation
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Solution Overview
Problem
Current storage systems face prolonged downtime and exposure to secondary failures during failover, as the process of resynchronizing data between primary and secondary storage systems after a failover event can take hours or days, leaving only one copy of data vulnerable to further failures.
Innovation Solution
Implementing an automated asynchronous data replication process that synchronizes updates from the secondary storage system to the primary system during failover, allowing I/O requests to be redirected to the secondary system while maintaining data consistency, and transitioning to synchronous replication once the primary system is fully operational.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If manual resynchronization is performed after failover, then data consistency is restored, but downtime is prolonged and the system remains vulnerable to secondary failures
Solution Approach 1:
The system performs preliminary actions by automatically initiating resynchronization of operable volumes immediately after failover occurs, before the primary system is fully repaired. This preliminary data collection and transfer process reduces the subsequent resynchronization time when the primary system recovers, thereby reducing overall downtime while maintaining data consistency.
2Reliability
If full resynchronization is performed for all primary storage devices, then data consistency is ensured, but the resynchronization process takes hours or days
Solution Approach 1:
The system segments the resynchronization process by identifying and separating operable primary storage devices from inoperable ones. Only operable volumes are resynchronized during the failover period, while inoperable volumes are deferred until the primary system is repaired. This segmentation dramatically reduces resynchronization time and improves productivity while maintaining data consistency for accessible data.
Solution Approach 2:
The system performs partial resynchronization by collecting diagnostic information and identifying which primary storage devices are still operable. Instead of resynchronizing all devices, it performs resynchronization only on the subset of operable devices during failover, achieving sufficient data consistency without the excessive time cost of full resynchronization.
3Ease of repair
If the primary storage system is taken offline for repair, then the inoperable device can be restored, but the system loses redundancy and becomes vulnerable to secondary failures
Solution Approach 1:
The system performs preliminary data collection and resynchronization actions while the primary system is still partially operational. By collecting diagnostic information and initiating resynchronization before the primary system is fully taken offline, the system maintains redundancy longer and reduces the vulnerability period during repair operations.
Data Source
AI summary
Provided are a computer program product, system, and method for performing a failover between a first storage system and a second storage system. Data is synchronized between the first storage system and the second storage system. A failover is performed from the first storage system to the second storage system in response to a failover event at the first storage system while synchronizing the data. A determination is made that a first storage unit of the first storage system is inoperable and that that a second storage unit of the first storage system is operable in response to the failover event. In response to determining that the second storage unit is operable, a resynchronization is initiated to copy updates to a second storage unit of the second storage system mirroring the second storage unit of the first storage system to the second storage unit of the first storage system.