Study And Implementation Of The Wide Area Network Storage Accelerating System

As the development of Internet, more and more applications need net backupservice. However, since the wide area network (WAN) has the attributes of highbandwidth, high latency, making it inapplicable to apply the normal net transportationprotocol efficiently. Moreover, in backup application, the two images of continuous twobackups have much in common. It will greately reduce bandwidth and the time windowof backup if we find out this identical data and only transport the others. Finally, inenterprise application, it is required to setup this system only in the gateway. However,if the system is setup in the gateway, the input of this system is just network data. Howto make use of this normal network data is still a problem.This paper starts from the view of network seven levels to solve the problemsabove. This paper’s will focus on the the presentation layer and the transportation layer.From the top down view, this paper’s work consists of three parts, network datade-duplication model in presentation layer, zip model for data out of order inpresentation layer and the reliable UDP model in transportation layer.In the network data de-duplication model, it first uses the rabin sliding windowalgorithm used in normal byte caching method, moreover, in considering of the highdegree of similarity between two continuous backup images, the system tries tosubstitute these continuous rabin fingers to one2-level finger, which will greatly reducenetwork data.In the zip model for data out of order, since the bottom level’s input is out of order,the system can not use the normal zip method by referencing all the data before whenun-ziping. However, it is discovered that, the earlier the data has been sent out by thesender, the more likely the receiver has received it. The system uses this discovery toreference only the pre n’th-m’th packets to n’th packets. This idea gives a more real-timestream based zipping method.In the reliable UDP model, instead of using TCP which will create much morelatency in WAN than UDP, the system builds a simple reliable UDP protocol with asimple flow control and bandwidth detection method. In a word, this paper improves original methods in three parts to build a backupspeedup system in WAN. Finally, this paper builds a simple verification system to verifythese innovation points. And the experiment data shows that these innovations indeedenhance the system performance greatly.