CXL Storage Device Coherence Circuit Reduces Host Communication Overhead
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Solution Overview
Problem
In a data center with multiple hosts and storage devices connected through a CXL switch, maintaining metadata coherence across hosts leads to communication overhead, diminishing storage system performance.
Innovation Solution
A storage device with a controller that includes a CXL interface circuit, a NAND interface circuit, a DRAM controller, and a coherence circuit. The coherence circuit detects changes in metadata managed by one host and transmits update information to other sharing hosts through the CXL switch, maintaining metadata coherence without individual host communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple hosts maintain metadata coherence through individual communications, then metadata coherence is maintained, but communication overhead increases and storage system performance diminishes
Solution Approach 1:
The storage device acts as an intermediary between hosts to maintain metadata coherence. The controller detects metadata changes from one host and automatically transmits update information to other sharing hosts through the CXL switch, eliminating the need for direct host-to-host communication and reducing communication overhead
Solution Approach 2:
The storage device autonomously manages metadata coherence by detecting changes in its own metadata and proactively notifying other hosts. This self-service mechanism eliminates the need for hosts to actively communicate with each other, thereby reducing system complexity and communication overhead
2Stability of the object's composition
If hosts communicate individually to maintain metadata coherence, then consistency is achieved, but communication overhead increases
Solution Approach 1:
The storage device serves as a mediator that receives metadata change notifications from one host and automatically propagates these updates to other hosts through the CXL switch, eliminating direct host communication and reducing overall communication traffic in the system
Solution Approach 2:
The storage device proactively detects metadata changes and immediately transmits update information to other hosts before inconsistencies can occur. This preliminary action ensures metadata consistency is maintained without requiring continuous host communication
Data Source
AI summary
Disclosed is an operation method of a storage device which is connected to a compute express link (CXL) switch. The method includes receiving a first access request from a first host through the CXL switch, performing an operation corresponding to the first access request, detecting a change in first metadata managed by the first host, based on the first access request, and transmitting first update information corresponding to the change in the first metadata to a second host sharing the storage device through the CXL switch.