LUN Migration Background Copy Throttling
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Solution Overview
Problem
Storage systems face significant downtime and performance issues during Logical Unit (LUN) migration between aggregates, as existing methods require suspension of data access and substantial copying times, which are unacceptable in modern IT environments.
Innovation Solution
A system and method for LUN migration that creates a new destination LUN and uses a background copy process to copy data while allowing continued access to the source LUN, with optional mirroring for increased consistency, minimizing downtime and maintaining system performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LUN migration is performed using existing methods, then data is copied from source to destination, but data access must be suspended and downtime is substantial
Solution Approach 1:
The patent creates a destination LUN before suspending data access, and initiates the copy operation in advance. By preparing the destination LUN and starting the migration process before the actual switchover, the system minimizes the time that data access is suspended while ensuring a ready destination is available for immediate use.
Solution Approach 2:
The patent implements a copy operation that duplicates data from the source LUN to the destination LUN while allowing continued access to the source. This copying mechanism enables the migration to proceed in the background without interrupting client access, resolving the contradiction between data access continuity and migration completion.
2Productivity
If LUN migration is performed using existing methods, then data is copied from source to destination, but system performance deteriorates during migration
Solution Approach 1:
The patent implements a dynamic copy operation that can adjust its throughput based on system conditions. The copy process is designed to operate in the background with variable speed, allowing the system to maintain overall performance while progressing the migration. This dynamic approach resolves the contradiction by enabling migration speed to be optimized without causing excessive performance degradation.
3Loss of time
If LUN migration is performed using existing methods, then data access is suspended, but this causes unacceptable downtime in modern IT environments
Solution Approach 1:
The patent enables data access to continue uninterrupted during the migration process. Clients can read from and write to the source LUN while the copy operation proceeds in the background. This continuity of useful action eliminates access suspension entirely, resolving the contradiction between minimizing downtime and maintaining operational simplicity.
Data Source
AI summary
A system and method for lun migration between data containers, such as aggregates of a storage system is provided. A new destination lun is created on a destination aggregate. A background copy process is then started that copies all data from a source lun on a source aggregate to the destination lun. The storage system continues to process client-originated data access requests directed to the source lun while the background copying continues. Once all the data of the source lun has been copied to the destination lun, processing of data access requests to the lun(s) is quiesced by the storage system. Lun maps of the storage system are then updated and processing of the client-originated data access requests is resumed with those requests now being directed to the destination lun.