Storage Volume Migration via Persistent Reservation Transfer
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Solution Overview
Problem
Existing technologies for migrating data storage volumes between storage arrays often require stopping host I/O requests, identity spoofing, or are not easily customizable, leading to disruptions and complexity in seamless volume migration.
Innovation Solution
The technology involves disabling the source volume, transferring persistent reservation information from the source to the destination storage array, and modifying active paths in host computers to redirect I/O requests, allowing seamless migration without stopping host I/O requests or identity spoofing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If previous volume migration technologies are used, then volume migration can be achieved, but host I/O requests must be stopped during migration causing application disruption
Solution Approach 1:
The patent applies preliminary action by pre-configuring the destination storage array with the volume's identity information before migration begins. This allows the destination array to be ready to immediately accept I/O requests once the source volume is disconnected, eliminating service interruption. The destination array is prepared in advance with all necessary configuration data including volume identifiers, access permissions, and path information.
2Adaptability or versatility
If identity spoofing is used in volume migration, then multi-pathing software can treat source and destination as different paths to the same volume, but this requires application software awareness and customization
Solution Approach 1:
The patent applies copying by creating a copy of the source volume's identity information and transferring it to the destination storage array. Instead of spoofing identities or requiring application-aware customization, the destination array receives a complete copy of the volume's identification data, permissions, and access control information. This allows standard multi-pathing software to automatically recognize the destination as a valid path without requiring any application software modifications or awareness of the migration process.
3Ease of operation
If native multi-pathing software is used, then standard volume migration can be performed, but seamless migration without interruption is not easily achievable
Solution Approach 1:
The patent introduces an intermediary mechanism where the storage array itself acts as the mediator between the source and destination volumes during migration. The storage array's controller manages the identity information transfer and coordinates the switching between source and destination paths. This intermediary approach within the storage array eliminates the need for complex external migration tools or highly customized multi-pathing software, enabling seamless migration using standard infrastructure while reducing overall system complexity.
Data Source
AI summary
While migrating a source volume to a destination storage array, disabling the source volume causes a source storage array to send a non-standard failure status code to all host computers in a cluster that includes the source storage array and the destination storage array. While the source volume is disabled with regard to standard host I/O requests received from host computers in the cluster, in response to receipt of the non-standard failure status code, a customized plugin added to the host computers transfers persistent reservation information to the destination storage array using non-standard read and set persistent reservation information commands. The destination volume is then enabled to process host I/O requests in accordance with the transferred persistent reservation information, and an active path for accessing the source volume is modified in each one of the host computers in the cluster to indicate the destination volume in the destination storage array.