Storage Virtualization Data Migration Without Host Software
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Solution Overview
Problem
Existing storage virtualization systems face challenges in minimizing downtime during data migration from source to destination storage, as they often require host-based software and disrupt user services.
Innovation Solution
The implementation of a storage virtualization method using 'pass-through' logical units, which allows data migration without adding software to the host, by collecting information on backend logical units, presenting them to the host through a virtual target, disconnecting the direct path, and migrating data transparently, while maintaining the same unique ID and personality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If data migration is performed using traditional storage virtualization systems, then data can be migrated from source to destination storage, but host-based software is required and user services are disrupted causing downtime
Solution Approach 1:
The system segments the storage access path into two distinct modes: direct path mode where hosts access backend LUNs directly without storage virtualization software, and virtualized path mode where access goes through the storage virtualization application. This segmentation allows migration to occur in the virtualized path while direct path hosts remain undisturbed, eliminating service disruption and downtime.
Solution Approach 2:
The storage virtualization application acts as an intermediary between hosts and destination storage during migration. It collects backend LUN information, presents virtual LUNs to hosts, and manages data copying to destination storage without requiring host-based software or interrupting user services, thus resolving the contradiction between service continuity and migration time.
2Ease of manufacture
If host-based software is added for data migration, then data migration can be performed, but system complexity increases and ease of operation decreases
Solution Approach 1:
The invention extracts the storage virtualization software from the host system and consolidates it into a standalone storage virtualization application. This eliminates the need for host-based software while maintaining migration capabilities, reducing system complexity and simplifying deployment by requiring software installation on only one system rather than multiple hosts.
3Reliability
If direct path access is maintained for backend LUNs, then hosts can access storage directly, but data migration cannot occur transparently without disruption
Solution Approach 1:
The system dynamically switches between direct path access and virtualized path access based on migration requirements. During migration, the storage virtualization application presents virtual LUNs that redirect access through the virtualization layer, enabling transparent data migration while maintaining access reliability. After migration completion, the system can switch back to direct path mode, providing adaptability for both migration and normal operation.
Data Source
AI summary
Methods and apparatus for migrating data with minimal disruption in a storage virtualization system. In one embodiment, a method includes collecting information on a backend logical unit (LUN) having a direct path from a host, presenting the backend LUN to the host through a virtual target via the storage virtualization application, disconnecting the direct path from the host to the backend LUN so that the backend LUN is accessed by the host via the storage virtualization application transparently to the host, and migrating data from the backend LUN to a destination storage transparently to the host.