Storage Write Buffer Pattern Segmentation for VM I/O Interference
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Solution Overview
Problem
In virtualized systems, the semantic gap between host and guest operating systems leads to inefficient delivery of I/O requests due to write interference between virtual machines, causing performance degradation and failing to guarantee Service Level Objectives (SLO) for each virtual machine.
Innovation Solution
A storage apparatus with a write buffer and memory that identifies write patterns by comparing data size with a predetermined threshold, allowing sequential write requests to bypass the write buffer and allocating random write requests to the buffer, thereby managing write buffers based on distinct patterns to prevent interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If all write requests are allocated to the write buffer, then write buffer utilization increases, but write interference between virtual machines occurs causing performance degradation
Solution Approach 1:
The patent segments write requests into two categories: sequential write requests (bypassing the write buffer) and random write requests (allocated to the write buffer). This segmentation resolves the contradiction by directing different types of write operations through different paths, thereby maintaining high write buffer utilization for random writes while preventing write interference for sequential writes.
2Quantity of substance
If sequential write requests are allocated to the write buffer, then write buffer utilization increases, but write interference occurs causing performance degradation
Solution Approach 1:
The patent extracts sequential write requests from the write buffer allocation path and directs them to bypass the write buffer entirely. This extraction eliminates write interference caused by sequential writes while preserving write buffer capacity for random write requests, thereby resolving the performance degradation issue.
3Device complexity
If write requests are not distinguished by pattern, then allocation is simple, but write interference occurs due to mixed I/O patterns
Solution Approach 1:
The patent introduces dynamic classification of write requests based on their access patterns (sequential vs. random). The storage apparatus dynamically determines the appropriate allocation path for each write request by analyzing its pattern, thereby optimizing I/O performance without imposing significant complexity through a straightforward classification mechanism.
Data Source
AI summary
Provided are storage apparatuses for a virtualized system and methods for operating the same. A method for operating a storage apparatus having a write buffer and a memory includes receiving a write request from a virtual machine, identifying a write pattern corresponding to the received write request by comparing a write data size indicated by the write request with a predetermined threshold, and allocating the received write request differently based on the identified write pattern.