arcived articles 2000
Fibre Channel Network
(Imagine)
April, 2000

One good way to increase productivity is to let people use common resources. Computer files have been shared over Ethernet and ATM networks for some time. With the idea of sharing video files over the network come the requirements of greater bandwidths and storage capacity.

The Storage Area Network (SAN) is a data communications platform that interconnects a centralized storage device, server and multiple computer workstations.

Instead of the traditional network solution such as SCSI, SSA, ATM or Ethernet, Fibre Channel Arbitrated Loop is used to optimize the speed of the data transfer over the network. Fibre Channel Arbitrated Loop (FC-AL) is a loop topology in which all devices use the loop as a point to point connection to any other device on the loop. FC-AL gives up to 200Mbytes per second on dual loop or 100 Mbytes per second on single loop. This means that several workstations can work simultaneously without interfering with each other.

SAN is one of the fastest growing and exciting technologies in the computer industry today. The technology itself started in the middle of the 90’s and is recently starting to gain popularity with the users in large data processing areas. Inc.

Over the past year, Fibre Channel-Arbitrated Loop (FC-AL) has emerged as the high-speed, serial technology of choice for server-storage connectivity. It has become the most widely approved open standard for the SAN environment. This extensive acceptance is attributed to FC-AL’s high bandwidth, high scalability and to its unique ability to support multiple protocols, such as SCSI and IP, over a single physical connection. This enables the SAN infrastructure to serve as both a server interconnect and as a direct interface to storage devices and storage arrays.

The traditional approach for building a network includes on or multiple servers, computer workstations and a large amount of storage connected to the server. The data is transferred from the storage over the network to the server, processed by the server and is transferred to the workstations. Network activity such as growth in data intensive applications, increasing reliance on access to enterprise data, demand for real-time reaction and to process all the data to and from the network is challenging the capacity of traditional server-storage solutions. When the server processes every request for data, there is a risk that the increase of network traffic will cause the server to become a bottleneck. Another drawback of the server model is that the server is a single point of failure in the whole system.

Lack of sufficient capacity to service clients and maintain data availability is a further limitation of server based networks. There is no scalability (room) for long rapid growth, or flexibility to provide optimum balance of server and storage capacity.

Because FC-AL allows direct connection of a hard disk, tape library, or other storage device to the network, the storage can be externalized from the server. The centralized storage will be shared among multiple computer workstations without impacting the system performance. The network is comprised of workstations and centralized storage device, with the server simply managing the storage. The important note here is that server does not need to be dedicated station but can be any of the computer workstations on the network. The result is the server-less SAN.

In addition to the basic connectivity benefits of SAN, the new capabilities, which include compute clustering, topological flexibility, fault tolerance, high availability, and remote management, further elevate SAN’s ability to address the growing challenges of data-intensive applications such as video.

In the server-less SAN environment there are no limitations to the size of the total bandwidth. Note that the bandwidth is always limited to the physical FC-AL speed, which is 100 or 200 Mbytes per second, although with many connections working in the parallel the total bandwidth may be heavily increased.

The scalability is modular and it provides high availability and fault tolerance. Integration of other devices and management of the system is easy.

Applications such as multimedia and video editing are resulting in an enormous increase of the total storage capacity needed on the market. In addition to the growth potential of the actual data storage device, advanced SAN topologies can be created through hubs, switches, bridges and routers, to scale overall bandwidth, enhance availability, and enable advanced SAN application capabilities in storage management and load balancing.