Network Cache Server File System Design And Implementation

With the development of computer networks especially Internet, Web proxy, as a cache server, is used widely. And with the increasing speed of network and slow nature of disks, the delays of file system on which web proxy runs contribute high toward total response time as perceived by the proxy client.Web proxy usually runs on traditional file system, while traditional file system is not optimized for web proxy applications. So it can be inefficient in traditional system. Commercial cache servers often adopt special operating system, special file system and even dedicated hardware and their own web proxy applications to achieve higher performance while they lead to high cost.This thesis analyzes the characteristics of web proxy servers, designs and implements a lightweight dedicated file system library in user space optimized for web proxy application in Linux. Normal web proxy with minimal modification according to new interface of our file system can achieve high performance on traditional operating system and hardware.The file system this thesis bring utilizes some characteristics of web proxy, such as the fact that cached web pages do not change in size once cached and access permission do not change, and the reference locality. According to these characteristics we can save file's data in contiguous blocks on disk and reading/writing to contiguous blocks allows us to utilize a disk's bandwidth most and reduce the seek time. The cached data on web proxy is backup files of remote original servers. So utilizing this redundancy we can put meta data in memory to increase performance of file system.At first, this thesis introduces related technologies, and then the characteristics of proxy workload. According to these characteristics we introduces the design idea of dedicated file system. The interface and implementation are also discussed and simple testing result is given.