一個固態硬碟虛擬平台的設計與實作

Abstract

業界在對固態硬碟做雛形設計時，除了離線的靜態效能模擬之外，亦對線上的即時模擬有很強烈的需求。本研究基於建構一個即時的模擬環境，可在作業系統內造出一個虛擬磁碟，而對該虛擬磁碟的讀寫動作會即時地導入固態硬碟模擬器，並由模擬器算出所需的快閃記憶體動作，接著由此環境產生對應之時間延遲。此一模擬環境可讓使用者即時修改其固態硬碟的軟硬體設計，並立即以該虛擬固態硬碟進行線上存取，而提供設計者更直覺的效能觀感，並可立刻進行架構上的微調。此年度相關技術議題包括該模擬環境與作業系統互動的作業系統核心架構，以及如何利用少量真實記憶體來模擬大容量的固態硬碟的技術。

When prototyping the architecture and firmware of an SSD, we found that Industry also has strong demands for real-time (on-line) simulation in spite of off-line performance simulation. This project developed a real-time SSD simulation environment. Specifically, this simulation environment creates a virtual disk in the host operating system. Designers can read and write the virtual disk with ordinary applications, the virtual drive forwards the I/O requests to the SSD simulation tool, which computes how many flash operations and how much time these requests take, and then the virtual drive simulates the I/O latencies. This approach provides designs a more intuitive and responsive approach for prototyping the design of an SSD. The technical issues of this project year include the interaction between the host operating system and the virtual drive and a method to create a very large virtual disk with only a limited RAM overhead.