Storage Node Control Information Preservation During Migration
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Solution Overview
Problem
Existing storage systems face challenges in continuing volume migration during power outages, leading to loss of transient state information and requiring restarts, especially in software-defined storage systems without dedicated hardware.
Innovation Solution
A storage system configuration with non-volatile storage apparatuses and controllers that store and manage control information, allowing for seamless resumption of volume migration and snapshot operations even during power outages by storing control information in a redundant manner.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If control information is stored in volatile memory during volume migration, then the storage system can operate with general-purpose server apparatuses without dedicated hardware, but control information is lost when power is interrupted during migration
Solution Approach 1:
The patent applies preliminary action by storing control information in advance to a destination storage apparatus before migration completion. The migration controller stores control information including migration state in the destination storage apparatus during the migration process, ensuring that even if power is interrupted, the control information is preserved and migration can be resumed without restarting from scratch.
2Reliability
If migration control information is stored in non-volatile storage, then migration can be resumed after power outage, but system complexity increases due to additional storage requirements
Solution Approach 1:
The patent applies universality by making the destination storage apparatus serve multiple functions: it acts as both the destination for volume data migration and as a storage location for control information. This multi-functionality eliminates the need for separate dedicated storage for control information, thereby reducing system complexity while ensuring reliable migration resumption.
3Device complexity
If volume migration is restarted after power outage, then system simplicity is maintained, but migration time increases due to loss of transient state information
Solution Approach 1:
The patent applies preliminary action by storing control information including migration state in advance during the migration process. When power is interrupted and restored, the migration controller can read the previously stored control information and resume migration from the saved state, avoiding the need to restart migration from the beginning and thus reducing time loss.
4Reliability
If control information is stored in destination storage apparatus, then information is preserved during power outage, but data security risks increase due to exposure at destination
Solution Approach 1:
The patent applies taking out by extracting only the necessary control information (migration state, mapping relationships) from the complete volume data and storing it separately in the destination storage apparatus. This separation allows control information to be preserved for migration resumption while minimizing the exposure of sensitive complete volume data, thereby reducing security risks.
Data Source
AI summary
Disclosed is a storage system having a plurality of storage nodes, each of the storage nodes including: a non-volatile storage apparatus that stores control information regarding a volume; a capacity controller that performs control associated with writing information to and reading information from the storage apparatus; and a migration controller migrates the volume, in which when the volume is migrated between the storage nodes, the capacity controller updates the control information in response to the migration of the volume performed by the migration controller.