Shulou(Shulou.com)06/01 Report--

Classification of storage

According to the server type, it is divided into: closed system storage (closed system mainly refers to mainframe) open system storage (open system refers to servers based on window Unix Linux and other operating systems) open system storage is divided into: built-in storage and plug-in storage according to the connection mode: direct attached storage (DAS) and networked storage (FAS) According to the transport protocol, networked storage is divided into network access storage (NAS) and storage area network (SAN).

DAS storage (direct-attached storage)

DAS storage is very common in our lives, especially in small and medium-sized enterprises, the main application mode of DAS, the storage system is directly connected to the application server, in small and medium-sized enterprises, many data applications must be installed on the direct DAS memory. DAS storage relies more on the server host operating system for IO read, write and storage maintenance and management of data. Data backup and recovery require the use of server host resources (including CPU, system IO, etc.). Data backup usually takes up 20% of server host resources. Therefore, the daily data backup of many enterprises is often carried out late at night or when the business is not busy, so as not to affect the normal business operation. The larger the amount of data stored by DAS, the longer the backup and recovery time, and the greater the dependence and impact on the server hardware. The connection channel between the direct-connected storage and the server host uses SCSI connection. As the processing power of the server CPU becomes stronger and stronger, the storage hard disk space becomes larger and larger, and the number of disks in the array becomes more and more, the SCSI channel will become the IO bottleneck; the server host SCSI ID resources are limited, and the SCSI channel connection that can be established is limited. NAS storage (network access storage)

NAS storage is also known as additional storage, which, as the name implies, means that storage devices are added to a group of computers through a standard network topology such as Ethernet. NAS is a file-level storage method that focuses on helping workgroups and departmental organizations rapidly increase the demand for storage capacity. Nowadays, users use more functions of NAS to complete file sharing, picture sharing, movie sharing and so on. With the development of cloud computing, some NAS manufacturers have also launched cloud storage functions, which greatly facilitate the use of enterprises and individual users.

NAS products are true plug and play products. NAS devices generally support multi-computer platforms, and users enter the same documents through the protocols supported by the network, so NAS devices can be used in hybrid Lans without modification, and NAS is very flexible. A key issue in NAS is the bandwidth consumption during the backup process. NAS still uses the network for backup and recovery. One disadvantage of NAS is the transfer of storage transactions from parallel SCSI connections to the network, which means that LAN must handle storage disk requests including backups in addition to normal end-user transfers. SAN Storage area Network (San) Storage area Network, which connects the storage array to the server host through a fibre Channel switch, and finally becomes a dedicated storage network. After more than ten years of development, SAN has become quite mature and has become the de facto standard in the industry (but the fiber switch technology of different manufacturers is not exactly the same, and their servers and SAN storage are compatible). SAN provides an easy way to connect to an existing LAN and supports the widely used SCSI and IP protocols over the same physical channel. SAN is not limited by the layout of today's mainstream SCSI-based storage structures. Particularly important, with the explosive growth of storage capacity, SAN allows enterprises to increase its storage capacity independently. The SAN structure allows any server to connect to any storage array, so that the server can directly access the required data no matter where the data is placed. Because of the optical fiber interface, SAN also has higher bandwidth. The drawbacks of SAN are cost and complexity, especially in fiber channel. DAS storage is generally used in small and medium-sized enterprises, directly connected to the computer, NAS storage is added to the computer through Ethernet, SAN storage uses the FC interface, × × can be more storage. NAS+SAN will be the main storage solution in the future, that is, the popular unified storage at present. Since it is a centralized disk array, it supports the host system to access file-level data through the IP network or block data access over the SAN network through the optical fiber protocol.

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