High-speed transmission means that the SAN Switch is required for purchase

Source: Internet
Author: User

There are many things worth learning about SAN switches. Here we mainly introduce the precautions for choosing SAN switches. With the increasing number of network data and the frequency of network applications, many enterprises have begun to realize that they need to build their own storage system networks to meet the increasing data storage performance requirements. Currently, the most popular data storage Network is SANStorage Area Network (Storage Area Network), which means connecting the entire storage to the enterprise LAN where the server is located.

It is characterized by the use of fiber channels with high transmission rates to connect to the server network, or the internal components of the SAN network, so that the entire storage network has a very wide bandwidth, this guarantees high-performance data storage. In this SAN storage network, FC switches, also known as "fiber channel switches" and "fiber switches", play a key role. This is a new type of device, and there are too many differences with the Ethernet switches we usually see (mainly reflected in protocol support), so many readers, even enterprise users who have used the SAN storage network know about the SAN Switch.

To this end, this article will introduce the things you need to pay attention to when purchasing a SAN Switch. In fact, it will introduce the main features of the SAN Switch. First, let's have a brief understanding of the origins of the SAN switch, so that we can have a better understanding of the SAN Switch, no longer full of "mysterious" colors.

Origin of SAN Switches

Previously we saw that data storage is basically directly connected to several SCSI, IDE, and other disks on the server. This is what we often hear about as a direct connection storage (DAS) method. This point-to-point disk system shows that it is difficult to expand and the storage performance is difficult to improve. In addition, due to the physical performance constraints of the IDE and SCSI interfaces, the disk connected to it can only have a connection distance of less than 20 meters, which greatly limits the expansion of the disk storage system.

To solve these problems, network equipment vendors and standards experts began to consider developing a new type of storage technology to fundamentally solve the problem of the data transmission rate and connection distance of the DAS storage. In the beginning, people thought that the storage system was independent and put on the network node as a network device, which can greatly reduce the Data Storage Load of servers, it can greatly expand the disk storage system, which is the NAS network attached storage method later.

This storage method does solve the shortcomings of the previous DAS storage method to a large extent, and can meet the needs of most small and medium enterprises for local storage. Moreover, it is easy to use and adopts the same IP protocol as Ethernet. network administrators can easily master the deployment of NAS storage systems, which is widely welcomed by many enterprises. However, NAS still does not fundamentally solve the problem of disk storage performance and connection distance. In general, the disk storage performance has not been fundamentally improved, but only increased the network egress bandwidth.

Because NAS still has the above limitations, people continue to develop a new network storage method, which is the SAN storage method described earlier in this article. Shows the network structure. The most important feature of this storage method is the fiber Channel protocol that provides Gigabit serial network access for storage devices, then, on the fourth layer of the optical fiber channel protocol, the SCSI protocol for storage, the IP protocol for the network, and the Virtual Interface (VI) Protocol for the cluster mapped to the network architecture, in this way, network devices and channels of various bus types can be supported in many ways. The Optical Fiber Channel Protocol combines many advantages, such as a network range of up to 10 kilometers, you can use simple serial cables with multiple media, Gigabit network speeds, and multiple protocols on the same cable.

A san is a network composed of storage devices and system components. All communications are completed on a fiber channel network and can be used to centralize and share storage resources, instead of NAS storage, it is only a network device as a network node. SAN not only provides high-performance connections to data devices, but also improves data backup speed and redundant connections to the storage system, providing support for high-availability cluster systems. Simply put, a SAN is a dedicated fiber-channel network that connects storage devices and servers, but it has a similar architecture with Ethernet, it is also composed of servers supporting fiber channels, fiber channel card NICS), fiber channel hubs/switches, and fiber channel storage devices. Technically speaking, the three most important components of a SAN network are: Device interfaces (such as SCSI, fiber channel, and ESCON), connecting devices (switches, gateways, routers, hubs, etc.) and communication control protocols (such as IP addresses and SCSI ). These three components, coupled with additional storage devices and servers, constitute a SAN system.

Precautions for Fiber Channel Switch purchase

As vswitches are the core component of building a storage area network SAN, it is crucial to select the most suitable vswitch. Only the correct selection of the most suitable optical fiber switch for the Storage Area Network can improve the efficiency of enterprise information management and meet the most challenging requirements. From the previous introduction, we can clearly see that SAN networks are essentially different from traditional Ethernet networks. However, network equipment vendors have different understandings of SAN, therefore, a SAN system using multiple device interfaces and channel protocols has emerged. This is the SCSI, fiber channel, ESCON, FICON, and so on. The channel protocol also includes the fiber channel FC protocol, SCSI and FCIP protocol. These different interfaces and channel types determine the complexity of deploying the entire SAN Network System on devices. Below we will introduce several main considerations.

1. Brand Selection

Although we can see in the media that many vendors claim that SAN switches can be selected, this is actually an illusion that most manufacturers of SAN switches are OEM main brands. Currently, the main strengths of SAN switches include IBM, Brocade, Cisco, and McDATA. software vendors such as EMC are basically SAN Switch products of other OEMs. Because there are many oem san Switch products on the market, many users do not know which company to develop or produce the SAN Switch they have bought. Now you have to know the suppliers. Never buy a brand.

2. Channel Protocol Support

The channel protocols used by the SAN Switch vary according to the specific applications, such as the FC, SCSI, and FCIP protocols described earlier, different types of device interfaces are supported. The FC protocol is generally supported by all SAN switches, and the SCSI protocol may be supported by medium and low-end Optical Fiber switches. The FCIP protocol based on the Ethernet IP protocol is now supported by many manufacturers' SAN switches, because of its simple implementation cost, it is very popular with enterprise users. As shown in, Cisco has a multi-layer Optical Fiber Channel switch that fully supports the above channel protocol, Cisco MDS 9216.

3. Support for Interface Types

Different SAN switches may support different interface types, but the performance of different interface types is also different. You must be aware of the differences when purchasing them. For example, we know that the latest Ultra 320 interface can reach 320 MB/s, and the transmission distance is only 20 meters. It is usually a dedicated interface for connecting disk devices. Fiber Channel FC can currently provide 1 ~ 4 GB/s transmission rate can reach 10 GB/s), at least three times faster than SCSI. It is usually used for connecting server hosts to SAN switches, and some disks support FC interfaces; the Escon Interface Designed by IBM supports 200 Mb/s data rate in full duplex mode on Optical Fiber. This is generally an interface connecting server hosts or SAN switches. Based on different configurations, the Escon interface supports a transmission distance of 3 ~ 10 km, depending on the quality of the optical fiber and product features. FICON interfaces developed by IBM are currently the latest Interface Types and are also the connection interfaces between servers or SAN switches. It delivers 6 times faster than ESCON. The transmission distance is also more than 19 kilometers. However, many SAN switches support these interfaces at the same time.

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