Multi-Controller Storage via NVMe over RDMA
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Solution Overview
Problem
In centralized cloud storage systems, the existing architecture for processing multiple write requests in parallel leads to significant processing time and increased data failure due to frequent storing and transferring of application data before it is correctly written into the storage apparatus.
Innovation Solution
A multi-controller storage system utilizing the NVMe over RDMA protocol, where a host transfers application data directly from its main memory to a non-volatile memory through remote direct memory access, with space indicator information allowing efficient data writing into reserved spaces in secondary controllers, reducing the need for intermediate storage and transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If application data is stored in the primary controller's scratchpad memory before being transmitted to secondary controllers, then the write requests can be distributed and processed in parallel, but the processing time increases and data failure risk increases due to frequent storing and transferring
Solution Approach 1:
The patent extracts the scratchpad memory component from the primary controller and replaces it with direct RDMA memory access capability. This allows the host to directly access the secondary controller's memory space without intermediate storage, eliminating the time-consuming store-and-forward process while preserving parallel processing capability through direct memory pointers
Solution Approach 2:
The patent introduces RDMA (Remote Direct Memory Access) as an intermediary mechanism that enables direct memory access between the host and secondary controllers without involving the primary controller's scratchpad memory. This mediator allows data to be transferred directly to the final destination memory, eliminating unnecessary intermediate storage and reducing processing time
2Productivity
If application data is frequently stored and transferred through multiple controllers before being written to storage, then distributed processing can be achieved, but the reliability decreases due to increased data failure occurrence
Solution Approach 1:
The patent removes the intermediate storage step in the data path by extracting the scratchpad memory from the system architecture. Data now flows directly from host memory to secondary controller memory and then to storage, reducing the number of transfer points and associated failure risks while maintaining distributed processing
Solution Approach 2:
The patent implements preliminary action by having the secondary controller pre-allocate and report memory space information to the host before data transfer. This allows the host to directly write data to the correct memory location in one operation, eliminating the need for subsequent data movement and reducing the probability of data failure
3Ease of operation
If the primary controller centralizes all write requests and manages data distribution, then controller coordination is simplified, but the data transfer efficiency decreases due to additional storing and transferring steps
Solution Approach 1:
The patent introduces RDMA as a mediator that bypasses the primary controller for data transfer operations. While the primary controller still coordinates write request distribution, the actual data transfer occurs directly between host memory and secondary controller memory through RDMA, eliminating the speed penalty of intermediate storage and forwarding
Data Source
AI summary
A multi-controller storage system and a storage apparatus for performing data access to a non-volatile memory with multiple controllers are provided. When a host transmits a command to a first controller and the first controller assigns the command to a second controller, the first controller transfers data from the host to the second controller through the first controller through the non-volatile memory express over remote direct memory access protocol (NVMe over RDMA) to directly write the data into the second controller.