Research on network storage technology of small and medium-sized enterprises

0 Introduction

With the advent of the information society, how to make small and medium-sized enterprises users can also invest a small amount of money in the data storage to obtain greater storage space and data management? Networked storage is a better solution, and iSCSI technology is emerging, narrowing the distance between SMEs and sans (storage area networks). iSCSI storage Technology leverages the pervasive advantage of existing IP networks, allowing users to build sans over TCP/IP networks, increasing the ability of many SMEs to access storage devices directly. So that SMEs can also set up their own data storage system, and in the case of a small amount of funds to obtain better resource sharing, resource management applications.

1 Network Storage development process

To date, storage development has gone through three generations, namely Das (direct attached Storage, direct-attached storage), NAS (Network attached Storage, network-attached storage), SAN (Storage area Network, Storage Area Network). The power of development stems from the system's increasing demand for forwarding and storage. In a DAS system, a storage device is sent directly from the server to a storage device via a cable (usually a SCSI interface cable) and a server-connected I/O (input/input) request. Because of the simplicity of earlier networks, direct-attached storage was developed, but not to meet the requirements of mass storage and device sharing, and other storage technologies such as NAS and Sans emerged.

NAS systems include storage components (such as disk arrays) and embedded system software, which can support multiple application protocols and multiple operating systems, and are used in different network environments without modification to the network environment. NAS systems are directly connected to the network through the network interface, and simply configure the IP address to be shared by users on the network. A NAS storage System implements a file-level storage that is appropriate for transferring storage files and shared files over a LAN. But this kind of processing will occupy the host large amount of CPU resources, the file operation delay is quite large.

In contrast to NAS systems, SAN Systems are a technology that integrates storage devices, connectivity devices, and interfaces into a high-speed network, which is itself a storage network that takes on data storage tasks, and the San network is isolated from the LAN business Network, which does not consume business network bandwidth. In a SAN network, all data transfers are carried out in high-speed, high-bandwidth networks, and SAN storage enables block-level storage access to physical hardware directly, improving storage performance and upgrade capabilities.

The most essential difference between a NAS system and a SAN system is the location of the file management system. As shown in Figure 1, the File Management system (FS) is on each application server in the San structure, while the NAS is a network sharing protocol (for example, NFS, CIFS) for each application server.

Figure 1 Nas and San comparisons

Depending on the transport protocol and physical media used by the storage network, the SAN has two implementations of FC Sans and IP sans, and the Fcsan uses FC protocols to form storage networks through high-speed fibre Channel, a traditional San architecture. IP sans use iSCSI protocol, which brings together the advantages of IP openness and data block storage to achieve end-to-end SAN storage. The iSCSI port Speed has been upgraded from L Gbps to Gbps in 4 years, and will reach Gbps in the next 4-5 years, from the IETF organization's February 2003 announcement of formal adoption of the iSCSI standard. and FC storage technology since the development in 1988, although after 10 years of development, FC port speed is only 4 Gbps; the next-generation 8 Gbps FC storage Standard is also at a standstill and is discussing whether to stop FC development and instead adopt FCoE (FC over converged Enhanced Ethernet, Ethernet Fibre Channel) technology. and FCoE technology means that FC network will be eliminated, the SAN network completely unified to Ethernet IP technology.

2 IP SAN Technology Basics

The IP San consists of iSCSI initiator (iSCSI clients), iSCSI Target (iSCSI destination), and IP network switches, as shown in Figure 2.

Figure 2 IP San Network architecture

iSCSI clients usually refer to the front-end server, while the iSCSI destination refers to the back-end disk array. The transfer of data stored between the server and the disk array is achieved through the iSCSI (Internet SCSI) protocol. The iSCSI protocol defines the rules and methods for sending and receiving block-level storage data in TCP/IP networks, as shown in Figure 3.

Figure 3 Structure of the iSCSI data message