Components of Storage Area Network (SAN)
Components of Storage Area Network (SAN) involves 3 basic components:
(a). Server (b). Network Infrastructure (c). Storage
The above elements are classified into following elements like,
(1). Node port (2). Cables (3). Interconnection Devices (4). Storage Array, and (5). SAN Management Software
These are explained as following below.
1. Node port:
In fiber channel, devices like,
- Tape Libraries are referred as nodes
Nodes consists of ports for transmission between other nodes. Ports operate in Full-duplex data transmission mode with transmit(Tx) and Receive(Rx) link.
SAN implements optical fiber cabling. Copper cables are used for short distance connectivity and optical cables for long distance connection establishment.
There are 2 types of optical cables: Multi-mode fiber, and Single-mode fiber are as given as below.
- Multi-mode fiber:
Also called as MMF, as it carries multiple rays of light projected at different angles simultaneously onto the core of the cable. In MMF transmission, light beam travelling inside the cable tend to disperse and collide. This collision, weakens the signal strength after it travels certain distance, and it is called as modal dispersion.
MMF cables are used for distance up-to 500 meters because of signal degradation(attenuation) due to modal dispersion.
- Single-mode fiber:
Also called SMF, as it carries a single beam of light through the core of the fiber. Small core in the cable reduces modal dispersion. SMF cables are used for distance up-to 10 kilometers due to less attenuation. SMF is costlier than MMF.
Other than these cables, Standard Connectors (SC) and Lucent Connectors (LC) are commonly used fiber cables with data transmission speed up-to 1 Gbps and 4 Gbps respectively. Small Form-factor Pluggable (SFP) is an optical transceiver used in optical communication with transmission speed up-to 10 Gbps.
3. Interconnection Devices:
The commonly used interconnection devices in SAN are:
- Switches and
Hubs are communication devices used in fiber cable implementations. They connect nodes in loop or star topology.
Switches are more intelligent than hubs. They directly route data from one port to other. They are cheap and their performance is better than hubs.
Directors are larger than switches, used for data center implementations. Directors have high fault tolerance and high port count than switches.
4. Storage Array:
The fundamental purpose of a SAN is to provide host access to storage resources. SAN storage implementations provides:
- high availability and redundancy,
- improved performance,
- business continuity and
- multiple host connectivity.
5. SAN Management Software:
This software manages the interface between the host, interconnection devices and storage arrays. It includes key management functions like mapping of storage devices, switches, and logical partitioning of SAN, called zoning. It also manages the important components of SAN like storage devices and interconnection devices.
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