Multi-path Layer Protocol Endpoint Masking for Storage Transformation
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Solution Overview
Problem
Existing techniques fail to provide a non-disruptive mechanism for transforming logical storage devices from using one access protocol, such as SCSI, to another, like NVMe, without affecting the operation of storage systems.
Innovation Solution
A multi-path layer with MPIO drivers manages logical storage devices to present a single device identity, allowing seamless switching between SCSI and NVMe protocols by temporarily masking and unmasking protocol endpoints, ensuring continuous operation and data integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If data migration techniques are used to migrate data between two different logical storage devices using respective different access protocols, then data can be transferred between protocols, but the mechanism fails to provide effective transformation of a particular logical storage device from one access protocol to another without disrupting storage system operation
Solution Approach 1:
The storage device is segmented into two separate logical storage devices, each supporting a different access protocol (SCSI and NVMe). This allows the system to maintain both protocols simultaneously without requiring a complete transformation that would disrupt operations. The segmentation enables gradual migration and protocol coexistence.
Solution Approach 2:
A multi-path layer is introduced as an intermediary component that manages access to both SCSI and NVMe logical storage devices. This intermediary layer presents a unified device identity to upper layers while handling protocol-specific operations behind the scenes, enabling seamless protocol transformation without affecting application-level operations.
2Adaptability or versatility
If a logical storage device is transformed from one access protocol to another, then the access protocol can be updated, but this transformation disrupts the operation of the storage system and applications
Solution Approach 1:
The second logical storage device with the new access protocol is prepared in advance while the first device remains operational. Data is pre-migrated to the second device, and the multi-path layer is configured to recognize both devices. This preliminary setup allows the protocol transformation to occur without disrupting ongoing storage operations.
Solution Approach 2:
The system maintains continuous storage operations by keeping both logical storage devices active during the transition period. The multi-path layer ensures that I/O operations continue to flow without interruption, seamlessly switching between the old SCSI-based device and the new NVMe-based device, thereby eliminating downtime during protocol transformation.
3Adaptability or versatility
If multiple protocol endpoints are presented for the same device identity, then protocol flexibility is increased, but the complexity of managing multiple endpoints and masking/unmasking increases
Solution Approach 1:
The multi-path layer is designed with universal functionality to handle multiple access protocols (SCSI and NVMe) through a single unified interface. It presents multiple protocol endpoints for the same device identity while maintaining a consistent device view for upper layers. This universal design simplifies management by providing a single point of control for protocol-specific operations.
Data Source
AI summary
A host device discovers one or more first protocol endpoints presented by a storage system for a first logical storage device utilizing a first access protocol, and discovers one or more second protocol endpoints presented by the storage system for a second logical storage device utilizing a second access protocol. Responsive to determining that the first and second logical storage devices have a same device identity, the host device temporarily masks the one or more second protocol endpoints in a multi-path layer of the host device from one or more applications executing on the host device. In conjunction with a switchover from the first logical storage device to the second logical storage device, the host device ends the temporary masking in the multi-path layer and enables access of the one or more applications to the second logical storage device via the one or more second protocol endpoints.