Copy-Free Storage Volume Protocol Conversion
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Solution Overview
Problem
Existing methods for converting storage volumes from SCSI to NVMe access protocols are either disruptive and require complete outages or inefficient, as they involve host-based data copying, which is resource-intensive and time-consuming.
Innovation Solution
A method that leverages the NVMe offload mechanism and storage migration mechanisms like Storage vMotion, using a special copy offload to eliminate host data copy, by creating a data handle and token pair that allows metadata mirroring without copying underlying data, enabling a seamless and non-disruptive protocol switch.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If host-based data copying is used for protocol conversion, then data can be transferred from source to destination volume, but host CPU and memory resources are heavily consumed and conversion time increases
Solution Approach 1:
The patent introduces a storage array as an intermediary that performs protocol conversion and data copying between source and destination volumes, eliminating the need for host-based copying. The storage array's controller handles all data transfer operations, allowing the host to simply issue conversion commands without participating in the actual data movement, thus reducing host resource consumption while ensuring complete data transfer.
2Adaptability or versatility
If traditional protocol conversion methods are used, then storage volumes can be converted between access protocols, but the process requires complete outages and is disruptive to operations
Solution Approach 1:
The patent implements preliminary actions by creating a destination volume in advance within the same storage array, preparing the protocol conversion environment before actual conversion begins. The storage array pre-configures the destination volume with appropriate protocol handlers and data structures, so when conversion is initiated, it can proceed seamlessly without disrupting host operations or requiring outages.
Solution Approach 2:
The patent enables continuous operation during protocol conversion by allowing the host to maintain access to the source volume while the storage array simultaneously performs data copying and protocol conversion in the background. The conversion process runs continuously without interruption, and once complete, the host switches to the destination volume, ensuring no operational downtime.
3Reliability
If data copying is performed during protocol conversion, then destination volume can be populated, but the process is time-consuming and reduces productivity
Solution Approach 1:
The patent replaces the mechanical host-based data copying process with an automated storage array-based copying mechanism. The storage array controller implements optimized data transfer paths and parallel copying capabilities, substituting the slow, sequential host-based copy operations with high-speed, parallel transfers managed by the storage array's specialized hardware, thereby dramatically increasing conversion speed while ensuring data completeness.
Data Source
AI summary
A method is disclosed of copy-free, non-disruptive conversion of a storage volume from a first access protocol to a distinct second access protocol. In a preparatory step a destination volume accessible according to the second access protocol is created. A pairing of a token and a handle is created, the token representing data content of the source volume, the handle being associated with the token and usable to represent the source volume according to the second protocol. In response to a subsequent copy-with-handle command, and based on the pairing of the handle with the token, metadata of the destination volume is populated to reference, without copying, the underlying stored data, the destination volume thereafter functioning as the storage volume accessed using the second protocol.