on Hierarchical Storage System based on Wireless Mesh Network

This thesis according to this hot technique of Wireless Mesh Network day by day mature background, on the foundation of comprehending the basic theories of Wireless Mesh Network, we emphasizes a rightness how to keep enough bandwidth and band rate in much jump of the Mesh environment in certain analysis and research. Through the experiment test and carried on certain data analysis, put forward of construct a kind of new structure to solve this problem. Take the applied aspect of Wireless Mesh Network,we combine the point of this text research problem and the construction present condition of wireless city in the home and abroad, elaborate outstanding position of Wireless Mesh Network in the construction of wireless city and how to construct a wireless city. Explain the important meaning of Wireless Mesh Network in the next generation wireless network. Introduction In recent years, along with more and more the deployment of the large-scale wireless network Wireless Mesh Network (WMN) is more and more valued by people, especially the emergence of Wireless Mesh Network satisfied a social demand more [1], its conduct and actions a kind of new network structure, just become a hot point in the research of next generation wireless access. Nowadays, the development trend of storage systems tends to be of mass storage, low cost and high performance, while any kind of storage device, such as Non-Volatile Random Access Memory (NVRAM), Solid State Disk (SSD) and Hard Disk Drive (HDD) [2-3], cannot meet the needs of these demands mentioned above due to its intrinsic characteristics. Hybrid storage systems, built by making the most of the properties of different types of storage devices, are not only capable to substantially extend the storage capacity, but also able to remarkably improve the performance while keeping a low system cost. Therefore, hybrid storage is becoming the development direction of storage technology. But people discover the Wireless Mesh Network exists some baffling when large-scale deployed in actual, especially multiple hops problem, this problem cause of bandwidth degradation, radio interference and network latency. etc., these problems make the performance of Wireless Mesh Network descend a lot. Organization of the Text In this thesis, the concept, development history and challenges of hybrid storage systems are introduced, based on which a hybrid storage system named Trident is designed and implemented. The thesis is focused on the following aspects: (1)The development history of hybrid storage systems is studied and a deep analysis on the critical technology problems in hybrid storage system design is made. (2)Trident, a hybrid storage system based on NVRAM,SSD and HDD is designed and implemented, the issues of which includes architecture, mapping policy, hot data identification, data migration and so on. (3)Synthetic workload and production workload are used to test and compare the random and sequential access performance of HDD-only, Facebook Flash Cache, and Trident storage systems. International Conference on Materials Engineering and Information Technology Applications (MEITA 2015) © 2015. The authors Published by Atlantis Press 101 The cache hit rates are also compared between Flash Cache and Trident systems. The test results show that, to the Trident system, the sequential access performance is close to that of HDD-only storage system, the IOPS partially exceeds that of Flash Cache, and the cache hit rate is close to that of Flash Cache with fewer write to SSD compare to Flash Cache. This system is implemented as a kernel module in the Linux OS and is transparent to upper layer applications. The research achievement of this thesis provides a reference for the design and implementation of other hybrid storage systems. Design process According to the shortage of WLAN, this paper studied a architecture of wireless mesh network, which has wide applicability. In this paper, the wireless Mesh AP based on embedded system mentioned has compatibility and interoperability [4]. Clinux system is set up on embedded board JA76PF0. According to the design demand, on the platform realizes the wireless Mesh AP node function, wireless network card driver, network management and the security of the wireless Mesh AP. By wireless network driver program Madwifi, set the two wireless card for different working mode. So the wireless Mesh backbone network can connect to the client network. Through software download, configuration files modified and compile the transplant of hostapd daemon, network address translation, dynamic host allocation protocol, network time protocol. Realized wireless parameter configuration and management and the reasonable use of network resources in the process of the network. By ESS1D hidden, MAC address filtering technology and WPA encryption authentication technology, the wireless Mesh AP is safe in the process of network. (Fig. 1 and Table 1) Fig. 1 Characteristics differences among several storage devices Table 1 compared with NVRAM/ SSD/ HDD NVRAM FRAM 55NS 10MB SSD FLASH-BASED SSD 25US 100GB HDD SATA 8.5MS 1000GB SSD BBDRAM 70-100NS 1GB Once again, the AODV routing protocol is successfully portal to the embedded board and according to the actual need to study a improved AODV routing protocol based on the parameters of wireless communication link stability [5]. By modying source code, data structure of Nettilter, and hook function, realized transplant of AODV routing protocol. Trough testing the stability of the wireless communication link and routing based on the stability of wireless communication link, realized improved routing protocol. By the simulation test of AODV and improved AODV in NS, proved improved AODV is better at network throughput and packet loss rate than AODV. [6] Finally, we designed wireless Mesh AP configuration and management platform based on B/S. By set up Web server on embedded board JA76PF0 and the interaction of Web server with CGI, we can read anct configure the parameter in long. Trough function, system function and shell script command, we can read and configure the parameter of wireless Mesh AI. By html, JavaScript script and CSS, an