本文選題：計算系統(tǒng)虛擬化　切入點：磁盤I/O　出處：《華中科技大學》2012年碩士論文　論文類型：學位論文

【摘要】：在以機械磁盤為存儲介質(zhì)的計算機系統(tǒng)中，數(shù)據(jù)讀寫操作的效率和可靠性將直接影響整個計算機系統(tǒng)的性能和穩(wěn)定性。為了在存儲介質(zhì)的讀寫速度、容量以及成本價格方面做出權衡，現(xiàn)代計算機操作系統(tǒng)一般采取了以高速緩存、內(nèi)存以及機械磁盤所組成的三級存儲結構，操作系統(tǒng)會在內(nèi)存中專門開辟出一塊空間作為磁盤緩存。在這種結構中，磁盤數(shù)據(jù)寫操作的方法通常分為兩種：寫直達法和寫回法。如何在這兩種寫方法之間做出權衡以使得系統(tǒng)既具有較好的可靠性又具有較高的磁盤讀寫性能是一個亟待解決的問題。 基于開源虛擬化平臺Xen的內(nèi)存臟數(shù)據(jù)回寫系統(tǒng)(VWrite)利用計算機系統(tǒng)虛擬化環(huán)境的結構特點和用戶使用習慣，實現(xiàn)了一種兼有寫直達法和寫回法優(yōu)點的磁盤數(shù)據(jù)寫操作的方法。此方法通過修改虛擬機塊設備前后端驅動程序，在虛擬機管理器中為每個虛擬機建立塊級別的虛擬機磁盤緩存。虛擬機中的應用程序均采取寫直達的方式，將數(shù)據(jù)直接寫到位于虛擬機管理器的虛擬機磁盤緩存中，當虛擬機意外崩潰時，虛擬機管理器可以將對應的虛擬機磁盤緩存上的數(shù)據(jù)寫入物理磁盤，以防止虛擬機數(shù)據(jù)的意外丟失。同時，與傳統(tǒng)寫直達方式不同的是，虛擬機中的應用程序只需要將數(shù)據(jù)寫到磁盤緩存即可返回，無需等待數(shù)據(jù)被寫入慢速的物理磁盤，從而在保證虛擬機數(shù)據(jù)完整性的情況下大幅度提高了傳統(tǒng)寫直達法的效率。另外，此系統(tǒng)還做了以下工作來進一步提高虛擬機磁盤I/O的性能：在虛擬機管理器中選擇合適的磁盤I/O調(diào)度算法以減小其對虛擬機磁盤I/O的性能影響；將虛擬機磁盤緩存中的請求進行統(tǒng)一的排序和合并以提高虛擬機隨機磁盤I/O操作的性能；實現(xiàn)分時刷新策略以保證多個虛擬機對物理磁盤I/O帶寬的合理利用。 實驗結果表明，，VWrite系統(tǒng)能兼有寫回法和寫直達法的優(yōu)點，能夠為虛擬機提供高效率的磁盤讀寫操作，同時，在虛擬機系統(tǒng)突然宕機時也能保證其用戶數(shù)據(jù)的完整性和可靠性。
[Abstract]:In computer system with mechanical disk as storage medium, the efficiency and reliability of data read-write operation will directly affect the performance and stability of the whole computer system. In terms of capacity and cost, modern computer operating systems typically use a three-tier storage structure consisting of cache, memory, and mechanical disks. The operating system creates a special piece of space in memory for disk caching. In this structure, There are usually two ways to write disk data: write direct and write back. How to make a trade-off between these two writing methods so that the system has better reliability and higher disk read and write performance is a. An urgent problem. Based on the open source virtualization platform Xen, the memory dirty data write-back system (VWrite3) utilizes the structural characteristics of the virtualization environment of computer system and the usage habits of users. In this paper, a method of disk data writing with both the advantages of write direct method and write back method is implemented, which modifies the driver of the front and rear end of the virtual machine block device. Create a block level virtual machine disk cache for each virtual machine in the virtual machine manager. Applications in the virtual machine write the data directly to the virtual machine disk cache located in the virtual machine manager. When the virtual machine crashes unexpectedly, the virtual machine manager can write the data on the corresponding virtual machine disk cache to the physical disk to prevent the accidental loss of the virtual machine data. An application in a virtual machine simply writes the data to the disk cache and returns it without waiting for the data to be written to a slow physical disk. In order to ensure the integrity of the virtual machine data, greatly improve the efficiency of the traditional write direct method. The system also does the following work to further improve the performance of the virtual machine disk I / O: select the appropriate disk I / O scheduling algorithm in the virtual machine manager to reduce its impact on the virtual machine disk I / O performance; In order to improve the performance of random disk I / O operation in virtual machine, the request in virtual machine disk cache is sorted and merged uniformly, and a time-sharing refresh strategy is implemented to ensure the reasonable utilization of physical disk I / O bandwidth by multiple virtual machines. The experimental results show that the VWrite system has the advantages of both write-back and write-direct, and can provide high efficiency disk read and write operation for virtual machine. At the same time, the integrity and reliability of user data can be guaranteed when the virtual machine system goes down suddenly.
【學位授予單位】：華中科技大學
【學位級別】：碩士
【學位授予年份】：2012
【分類號】：TP333.1

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1 朱智林,左天軍,牛淑齡;基于日志的臟數(shù)據(jù)檢測與恢復[J];電子科技;2004年05期

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