Minutes of FC (Fibre Channel) and SCSI

Storage Area Network (SAN). The essence of these changes in the transition from local storage on hard disks or internal network file servers in a distributed storage of information in the external network. Hard drive, tape drive or optical drive can be directly connected to this network, which is based on the FC - protocol (Fibre Channel), along with switches, routers and servers, which connect storage systems into a single integrated network, built on the basis of many, many .

Generally, SAN - is a specialized storage area network in which traffic is distributed IO between servers and storage devices, eliminating traffic applications. This eliminates the problem of bottlenecks in the network using a single architecture for all applications. SAN can also directly connect multiple storage systems based on cluster technology, using the best achievements of the SAN- making and in the end perfectly meet the needs of disk and tape drives, one or more servers.

Fibre Channel. extremely important in the technology of building SAN. The SAN using high-speed connections FC cables to connect between the server and storage devices, resulting in data transfer rate up to a maximum of 200 Mbit \\ s in the dual configuration, or 100 Mbit \\ s in normal mode.
Fibre Channel (FC) connection can provide multiple servers while maintaining the length of the tire up to 10 miles without using any signal amplifying devices. In addition, the SAN are supported and displayed a lot of technologies and protocols (SCSI, HIPPI, IP, ATM, etc. ).

The main advantages of FC compared to more traditional models using. SCSI. :.

The first indicator value for SCSI, second to FC (Fibre Channel).
Data transfer rate: 40 Mbit / s, 100 Mbit / s.
Scalable: 15 devices, 126 (FC-AL) ( dial- in mode is practically unlimited ).
Max. Length: 10 feet ( rigid cables), 6.25 miles of light to connect the wires.
Supports hot swap: No Yes.
Connection: An expensive reconfiguration, hot-swappable.

Fibre Channel will remove restrictions on carrying capacity associated with SCSI, has enabled the creation of large networks in large companies, which include a large number of servers and disk arrays, and other intelligent storage devices.

FC-AL (Fibre Channel Arbitrated Loop) - a ring of fiber-optic link to an arbitration is called a loop controlled. It's such a network configuration data storage, which allows you to leave a free port switching devices, thus allowing to combine theoretically infinite number of equipment (of course practice imposes its reasonable limitation of this infinite). This effect is achieved by high- speed connection that allows using switches on ports open them for a short time, enough to communicate with high-speed devices. Switched network, thus, increase the overall throughput of the real network data storage, increasing the scalability. FC-SAN- network.

However, in the conventional configuration (FC-ALS) below the price per port, so organizations need to make an informed decision based on the need for scalability. FC-ALS can theoretically support up to 'only' 126 units, while maintaining the transmission rate between the equipment. Both FC interface supports hot-swapping.

In terms of control FC- network offering centralized backup and management of devices with multiple servers. Consolidation of control helps in the diagnosis of equipment faults or failures in backup. As a result, this affects the overall increase resiliency.

Thus, despite the high cost of SAN, built using FC, have obvious and significant advantages over SCSI.

In an early review, we consider the interface. iSCSI. That implements the transport protocol for SCSI, which operates over TCP. In a sense, this solution combines the advantages of SCSI and Fibre Channel technologies.