In the past, the data storage we saw was basically connected to a disk such as SCSI or IDE directly on the server. This is the DAS (Direct Attached Storage) method that we often hear about. This kind of peer-to-peer disk system obviously has the disadvantage that it is difficult to expand and storage performance is difficult to improve. Not only that, due to the physical performance of the IDE and SCSI interfaces, the disks connected to it usually have a connection distance of up to 20 meters, which greatly limits the expansion of the disk storage system.
In order to solve these many shortcomings of the above DAS storage methods, network equipment vendors and standards development experts began to consider the development of a new type of storage technology to fundamentally solve the transmission rate and connection distance of DAS storage. At first, people thought of a way to separate the storage system and put it on a network node as a network device. This can greatly reduce the data storage load of the server and greatly expand the disk storage system. This is the later NAS (network). Additional storage) mode.
This kind of storage method does solve the problem of the previous DAS storage method to a considerable extent, and can meet the needs of most small and medium-sized enterprises for local storage. Moreover, its biggest feature is that it is simple and easy to use. It uses the same IP protocol as Ethernet. Network administrators can easily grasp the deployment of NAS storage systems and are widely welcomed by many enterprises. However, NAS still does not fundamentally solve the problem of disk storage performance and connection distance. In general, disk storage performance has not been fundamentally improved, but the network export bandwidth has been increased.
It is precisely because NAS still has these shortcomings, so people continue to develop a new way of network storage, that is, the SAN storage method introduced earlier in this article. The network structure is shown below. The biggest feature of this storage method is the Fibre Channel protocol, which provides Gigabit serial network access for storage devices, and then Fibre Channel-based on the fourth layer of the Fibre Channel protocol. The SCSI protocol for storage, the IP protocol for the network, and the virtual interface (VI) protocol for clustering mapped to the network architecture can support network devices and channels of various bus types in many ways. The Fibre Channel protocol combines many advantages, such as a network-wide maximum distance of up to 10 kilometers, a simple serial cable with multiple media, a Gigabit network speed, and the ability to use multiple protocols simultaneously on the same cable.
A SAN is a network of storage devices and system components. All communication is done on a Fibre Channel network. It can be used to centralize and share storage resources, instead of being a network node instead of NAS storage. Network equipment. SANs not only provide high-performance connectivity to data devices, increase data backup speeds, but also add redundant connectivity to storage systems, providing support for highly available cluster systems. Simply put, a SAN is a dedicated Fibre Channel network that connects storage devices and servers (unlike Ethernet), but it has a similar architecture to Ethernet, but also supports Fibre Channel servers, Fibre Channel cards (NICs), and Fibre Channel. Hub/switch and Fibre Channel storage. Technically speaking, the three most important components of a SAN network are: device interfaces (such as SCSI, Fibre Channel, ESCON, etc.), connected devices (switches, gateways, routers, Hubs, etc.) and communication control protocols (such as IP and SCSI). Wait). These three components, together with additional storage devices and servers, form a SAN system.
As enterprise network data continues to increase and network applications become more frequent, many organizations are beginning to realize the need to build their own storage system networks to meet the ever-increasing demands of data storage performance. Currently, the most popular data storage network is a SAN (Storage Area Network), which means that the entire storage is connected to the local area network of the server as a separate network.