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This article introduces the relevant knowledge of "the comparison of DAS, NAS and SAN storage technologies". In the operation of actual cases, many people will encounter such a dilemma, so let the editor lead you to learn how to deal with these situations. I hope you can read it carefully and be able to achieve something!

What is NAS?

Network storage device (Network Attached Storage,NAS) is the name of a special data storage technology, which can be directly connected to the computer network and provides centralized data access services for users of different operating systems.

The difference between NAS and traditional file storage services or direct storage devices is that the operating system and software on NAS devices only provide data storage, data access, and related management functions; in addition, NAS devices also provide more than one file transfer protocol. NAS systems usually have more than one hard disk, and like traditional file servers, they are usually composed of RAID to provide services; with NAS, other servers on the network no longer have to function as file servers. There are many types of NAS. It can be a mass-produced embedded device, or it can execute NAS software on ordinary computers.

NAS uses file-based communication protocols, such as NFS (common on UNIX systems) or SMB (commonly used on Windows systems). NAS uses file-based communication protocols, while storage area networks (SAN) use block-based communication protocols, usually converted to fibre Channel or iSCSI through SCSI.

NAS devices usually use a stripped-down version of the operating system, providing only the simplest file services and its related communication protocols; for example, an open source NAS software called FreeNAS uses a stripped-down version of FreeBSD, which can be executed on ordinary computer hardware, while commercial embedded devices use closed-source operating systems and communication protocol programs.

To put it simply, NAS is a network storage server that provides document sharing services on the network.

Network structure of NAS

NAS storage uses Ethernet interface to access the existing Ethernet network directly to realize data sharing. Deployment is flexible and does not change the existing network structure.

Advantages and disadvantages of NAS Stora

Advantages of NAS:

NAS devices generally support multi-computer platforms, and users can access the same documents through network support protocols, so NAS devices can be used in hybrid Unix/Windows NT Lans without modification.

Second, the physical location of NAS devices is also flexible. They can be placed in a workgroup, close to the application server in the data center, or they can be placed in another location and connected to the network through a physical link. Without the intervention of the application server, NAS devices allow users to access data on the network, which can not only reduce the overhead of CPU, but also significantly improve the performance of the network.

It has good adaptability to the existing network environment. NAS devices basically have no special requirements and restrictions on the enterprise network environment, so it is very convenient to add NAS devices to the existing network environment. This is because the operating systems and network protocols supported by NAS have been well supported in the network, and the addition of NAS devices will not cause new network support problems.

High scalability. The high scalability of NAS devices satisfies the growing storage needs of enterprises. NAS can be extended by adding a node and network device (true plug and play, and the deployment location is very flexible), basically starting the NAS device, running the corresponding network file system, and connecting the NAS device to the network environment.

NAS cluster technology forms like a NAS device through a set of NAS devices. NAS cluster technology provides a certain storage diversion, so that different NAS devices can work at the same time to meet the storage needs of network storage, thus improving the overall performance of the NAS system and solving the problem that the scalability and management of multiple NAS systems tend to be complex.

Manageability. NAS itself is designed for the internal network of the enterprise, and realizes the data sharing under heterogeneous platforms, so the cost of using and maintaining NAS is relatively low, and the management and maintenance work is relatively simple. Users only need some simple initial setup and management, NAS devices can run well.

Rich applications based on Web Services

NAS storage is a network file server based on TCP/IP protocol, so in addition to providing basic NFS, SMB and other network sharing services, it can also provide some advanced network applications according to different NAS storage devices, as shown in the following figure NAS

At the same time, it provides TCP/IP protocol-based network services such as file sharing service, FTP service, web service, log server, print server and backup server on a NAS device. For example, it has a great advantage in monitoring storage deployment.

SAN (Storage area Network) is connected to a group of computers via fibre Channel. Multi-host connectivity is provided in this network, but not through a standard network topology.

High bandwidth: the structure of SAN allows any server to connect to any storage array, so that no matter where the data is placed, the server can directly access the required data. Because of the optical fiber interface, SAN also has higher bandwidth.

Independent storage network: because the SAN solution strips storage functions from basic functions, running backup operations does not need to consider their impact on the overall performance of the network.

Ease of management: the SAN solution also simplifies management and centralized control, especially when all storage devices are clustered together.

Remote deployment: the optical interface provides a connection length of 50 kilometers, which makes it very easy to achieve physically separate storage that is not in the computer room.

SAN is mainly used in the working environment with large storage capacity, such as ISP, bank and so on. The biggest disadvantage is the high cost.

Summary

According to the different characteristics of DAS, NAS and SAN, DAS and SAN are disk allocation based on storage space, which is based on the storage mode at the hardware level, while NAS is based on the storage mode at the application level, which can be summarized according to the application environment.

DAS mostly uses SCSI or SAS interface. Due to the singleness and high performance of deployment nodes, it is suitable for enterprise applications with a single node or servers with scattered geographical locations. DAS is currently being used less and less due to deployment limitations.

NAS uses the existing Ethernet network, so the deployment is flexible and the cost of deployment is very low. The characteristics based on TCP/IP protocol can provide rich network services and provide data storage and backup in the form of files. However, TCP/IP protocol determines that the data packaging and unpacking of data transmission will take up system resources. In addition, the transmission rate is limited by the speed of Ethernet, so it is not suitable for enterprise applications. It is usually deployed in departmental applications.

SAN storage uses optical fiber network for transmission, and is independent of the application network, and can provide very high bandwidth. Data transmission is based on block protocol, so it can be transmitted directly without data processing, so its performance is the best. In addition, optical fiber lines can provide long-distance high-bandwidth links, which can achieve remote disaster recovery applications in data centers, but the deployment cost is high. Therefore, SAN storage is mostly used in enterprise storage deployment.

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