USB 3.0 網路儲存系統之設計與實作

Abstract

網路儲存裝置 (Network attached storage) 提供簡易的操作介面及多樣化的服務 在近年來愈來愈受到歡迎，在僅僅提供透過網路網頁做為必要設定介面外，減少 多餘的輸出輸入差介面也使得價格更為使用者所接受。另一特點為使用內接式硬 碟做為資料儲存媒體，其高速存取且價廉的優點雖廣為消費者所接受，然而硬碟 遇到空間不夠，升級更換時不易拆除的缺點，成為可以改善的重點目標。

在本篇論文中，我們將建立一以USB3.0為主要儲存裝置的網路儲存裝置，從最 先公板選擇到嵌入式系統安裝，以及所需要的各種網路服務軟體，本篇論文會針 對外接式硬碟為重點，將其容易拆除既是優點也是缺點的面向，透過軟體的方 式，在惡意或無意拔除USB3.0硬碟的情形下，將使用者的服務需求，重新導向 到另一台網路儲存裝置，讓使用者感覺不出網路服務中斷，並且在USB3.0硬碟 重新接回的情況下，重新存取原本的資料硬碟。如此一來便能讓USB3.0的高速 存取的優點突顯出來，也能讓使用者在網路儲存裝置的主要儲存媒體上，有多一 種的選擇。

當網路儲存裝置有能力處理外接硬碟被拔除，這也意味著對所以類似裝置而言， 不管是否有意的拔除硬碟或是硬碟故障，本機都有能力將網路服務重新導向，成 為管理網路服務方法之一。

Generally, retail NAS with USB ports are not used for primary access as data storage. In this thesis, a NAS device will be built based on USB 3.0 as the primary hard drive. from selecting the evaluation board and installing the embedded system and general services on a NAS device. We are targeting the advantages of being fast and convenient that a removable external hard drive has. On the other hand, the services will be temporarily unavailable due to USB is easy to be removed. In order to deal with this possible disadvantage, our idea is to redirect the services to any other NAS servers in the neighborhoods and the users won’t notice that they are accessing another NAS.

Our NAS device, the MiraBox, is a very tiny box, equipped with Marvell Armada 370 SoC 1.2GHz single-core, 1GB DDR3, 1GB NAND flash, two microSD expansion slots, and the most important two USB 3.0 ports. The affordable price and the various I/O modules are needed. Moreover, both two USB ports and two Gigabit Ethernet ports make MiraBox not only a NAS device but also a classroom server. However, there are two disadvantages found for now: the drivers and source code are dated and are not supported in Linux 3.0; after serving 2 ~ 3 hours, its high clock rate of CPU causes the device over temperature without system crash.

MiraBox uses the most popular OS Linux as the embedded system. The upper layer software source code and documents are easy to find. There are plenty of discussion groups for specific topics in the internet and anonymous programmers are dedicated to the open source. Although the drivers may not be supported by the lasted Linux kernel, the third party manufacturers are developing device drivers for catching up their own specific hardware devices.

The prospective advantages of MiraBox are: 1) Up to date hardware capacity. 2) Plenty I/O interfaces including USB 3.0 which is the target in this thesis. 3) Drivers support by third party manufacturer. 4) General used embedded system OS, Linux. 5) Not alone software development community. 6) Affordable price. On the contrary, the disadvantage is the warning of the overheat problem. In this thesis, the MiraBox is chosen to be the target board for designing and developing the redirect theory. The redirect theory turns the characteristic of being easy to remove into a new viewpoint for USB based NAS or even all NAS. No matter the root cause of being a temporary unavailable service is physical storage removement or services redirection intentionally, the redirect theory will be a general management method for NAS.