MPIO Driver Signature Resolution for Storage Migration
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Solution Overview
Problem
Conventional storage migration techniques face issues with file system signature problems when migrating logical storage volumes between storage systems, leading to degraded performance due to incorrect identification of source and target devices having the same file system signature.
Innovation Solution
The implementation of a multi-path input-output (MPIO) driver that updates the management header of the target logical storage device to include the source device's identifier, allowing applications to continue seeing the source device as a single entity until a reboot or file system remount, thereby avoiding file system signature issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If automated seamless migration is performed without spoofing source logical storage device identifiers, then migration can be completed, but file system signature issues arise when source and target devices have the same signature, causing the host to mark one as a copy of the other
Solution Approach 1:
The MPIO driver acts as an intermediary between the host application and the storage devices. It intercepts reads to the management header and returns the source device identifier instead of the target device identifier, thereby mediating the identification conflict and preventing the host from detecting duplicate file system signatures
Solution Approach 2:
The MPIO driver copies the source device identifier and returns it in response to reads of the target device's management header. This creates a virtual copy of the source identifier that allows the host to continue seeing the target device as the source device, avoiding identification conflicts
2Reliability
If device identifiers are spoofed during migration, then file system signature issues are avoided, but device complexity increases due to identifier management overhead
Solution Approach 1:
The MPIO driver automatically manages the identifier substitution without requiring external configuration or manual intervention. It self-services the identification conflict by intercepting and modifying reads to the management header, eliminating the need for complex external identifier management mechanisms
3Measurement precision
If the host device detects duplicate file system signatures, then it marks one device as a copy, but this degrades system performance by disrupting normal operation
Solution Approach 1:
The MPIO driver performs preliminary anti-action by preemptively substituting the source device identifier in response to reads of the target device's management header. This prevents the host from ever detecting the duplicate file system signature, thereby preventing the performance-degrading marking action before it can occur
Data Source
AI summary
An apparatus comprises at least one processing device comprising a processor coupled to a memory. The processing device is configured to control performance of a migration process in which a source logical storage device of a first storage system is migrated to a target logical storage device of a second storage system. In conjunction with the migration process, the processing device is further configured to update a management header of the target logical storage device to include an identifier of the target logical storage device, to store an identifier of the source logical storage device, and responsive to a read of the management header of the target logical storage device, to return the identifier of the source logical storage device in place of the identifier of the target logical storage device. Other illustrative embodiments include methods and computer program products.