What are the current mainstream storage technologies?

The traditional storage technology is DAS, which directly connects the storage device to the server, and is completely centered on the server as an integral part of the server. Storage devices used for DAS can be magnetic tapes, magnetic disks, magnetic disk displays, and tape libraries. Typical DAS storage devices are various types of magnetic disk displays.

Current network storage technologies include NAS, SAN, and ISCSI. NAS is based on TCP / IP protocol to provide file storage service; SAN is mainly based on Fibre Channel, data block-oriented storage, can be seen as an extension of the traditional bus; ISCSI is the first two technologies in TCP / IP network On the fusion, the technology of encapsulating the data block-oriented SCSI protocol in the TCP / IP package for transmission on the TCP / IP network.

Analysis and introduction of the characteristics of various storage technologies:

All along, the storage area network SAN used to store data is based on Fibre Channel (FC, Fibre-Clannel) technology, which provides high-performance block data access solutions for storage domain applications. Due to the application of IP in local area networks and wide area networks and good technical support, long-distance block-level storage can also be achieved in IP networks. The IP protocol replaces the Fibre Channel protocol to form IP-based SAN storage. With its low cost, high cost performance, unlimited distance, and difficulty in forming information islands, IPSAN has received more and more attention and applications. Several commonly used storage methods Because the early network is very simple, direct-attached storage (DAS) is the first network storage system to be adopted. In the DAS storage architecture, in order to avoid a single point of error, usually multiple servers share a storage system. When it is necessary to increase the storage capacity of the system, the method of increasing the disk array (RAID) is generally adopted. DAS used to be a popular storage system, but it could not meet the needs of large-capacity storage, so other storage technologies such as NAS and SAN appeared. The network storage system includes a file server and storage device components. The NAS has pre-configured storage devices to allow the main server to "free" from file I / O operations. The server is regarded as an optimized file system, and the operating system is no longer Realize the calculation function, only provide the file system function, and the client directly exchanges data between the NAS system and the storage device. The NAS directly runs the file system, such as NFS / CIFS, etc. In addition, by setting the NAS, data can be shared between different clients (such as NT and Unix). Drives, tape drives or removable storage media and embedded system software, it can support multiple application protocols (such as NFS, CIFS, FTP, HTTP, etc.), and can also support various operating systems, such as Unix / windowsNT, etc., and It can be used in different network environments without any modification to the network environment. NAS products are directly connected to the network through network excuses. After simply configuring the IP address, they can be shared and used by users on the network. NAS is suitable for transferring stored files and shared files via LAN. This processing method will occupy a lot of CPU resources of the host, and the delay of file operations is quite large. The increase in data volume causes DAS and NAS to have the same problem, and it is not possible to increase storage devices without limit to improve storage capacity.

Compared with DAS and NAS storage, the advantage of SAN is that all data processing is not done by the server. SAN is a technology that integrates storage devices, connecting devices and interfaces in a high-speed network. It is itself a storage network , Undertook the task of data storage in the main network. In a SAN network, all data transmission is performed in a high-speed, high-bandwidth network. SAN storage implements block-level storage access to physical hardware directly, improving storage performance and upgradeability. According to the different transmission protocols and physical media used in the storage network, SAN is implemented by FCSAN, IPSAN and other multiple methods. FCSAN uses high-speed fiber channel to form the storage network, which is the mainstream technology of SAN. With the openness of Ethernet and IP and the advantages of block storage in many aspects, the IP protocol-iSCSI replaces the Fibre Channel protocol to achieve end-to-end SAN storage. iSCSI technology requires only low-cost investment, and can easily and quickly carry out interactive transmission and management of information and data. Compared with the previous network access storage, iSCSI solves the problems of openness, capacity, transmission speed, compatibility, security and so on. Its superior performance has attracted market attention and favor since its release date.