Das NAS SAN

Das (Direct Attached Storage) is a direct connection storage. Direct Connection means that there is no network between the server and the storage device. Our personal computer is the DAS, because the hard disk is directly connected to the computer. It can be seen that DAS is an old technology.

Network attached storage (NAS. For example, if you share a directory on a Linux computer so that other Linux customers can access the Directory through the NFS protocol, this computer is a NAs in a certain sense. If you install software on this computer so that Windows users (through CIFS) and Linux users (through NFS) can access the shared directories on this computer, then this computer becomes a complete NAs.

San (Storage Area Network), a storage area network. Is to connect the server and storage devices with fiber switches, storage devices through disk arrays and other technologies to form a network.

The following figure intuitively shows three storage technologies.

 

Good understanding of DAS, but it may be difficult to distinguish NAs from San. In fact, there are two differences between the two:

• Fiber Channel and Ethernet
• File System

Fiber Channel and Ethernet

NAS storage and servers are connected through normal Ethernet connections, while San and storage are connected through Febre channel.

File System

In the NAS example we mentioned earlier, a Linux computer shares some directories and allows different machines, such as Windows Linux UNIX Mac, to use shared directories, it becomes NAs. Note that the shared directory is a file system in Linux. That is to say, the NAS file system is here. For a SAN, its file system is on the server, and the server uses its own file system to control the storage on the San, except that it is connected through an optical fiber switch. Simply put, in NAS technology, in addition to servers and storage, additional operating systems are also required to manage storage. SAN does not require additional storage. It manages storage directly through the server's file system.