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Interface

Fibre Channel Concepts

Topologies

Hardware Components

Environmental Concerns

Software Components

Storage Area Network: Architecture

Media and Connectors

SAN media refers to the cables that can be used in a SAN environment. Two types of media can be utilized, copper or optical (short-wave or long-wave).

Copper cables are best suited for short local connections (up to 12m).
Short-wave fiber optic cables are typically used for medium and longer distance connections (up to 500m).
Long-wave fiber optic cables are used for distances up to 10K between Fibre Channel switches and bridges.

Copper vs. Fiber Optic

Both copper and fiber optic cables offer the same data transmission speeds, but fiber optic allows for much greater cable lengths. While fiber optic cables are more expensive than copper cables, they are generally considered more reliable. Characteristics of fiber optic cable include noise immunity, high data rates at long distance, no short circuits or sparks, wide temperature range, stable performance, and ever-decreasing costs.

Note: There is no difference in the performance of FC in copper, short-wave, or long-wave optical cabling; each supports 200MB/sec bandwidth full duplex.

Copper cables are less expensive than fiber optic cables, but encounter more reliability problems. Also, the distance allowed is generally shorter than with fiber optic cabling. One will generally see two types of copper cabling: coaxial and twisted pair, in lengths of 3, 6, or 12 meters.

Cable Nomenclature

Most cables in a SAN have some identifying characteristics stamped on them. The labels found on SAN cables help determine characteristics such as whether the cable is multi-mode or single-mode, or whether it's Open Fiber Control (OFC), or non-OFC.

Data communications cables are cataloged into specific nomenclatures, meaning subgroups within a naming convention. The graphic at right shows an example of the labeling you would find on a generic Fiber Optic cable. This graphic gives an example of cable nomenclature: 100-SM-LL-L, meaning 100 MB per second, single-mode, long-wave laser, long distance cable

The "100-SM-LL-L" label indicates a 100MB speed, single-mode fiber optic cable which uses long-wavelength laser and is rated for up to 10 KM. All of that information can be derived from its nomenclature.

Each of the entries defines a particular characteristic of a cable:

Speed is the data transmission speed in megabytes per second.
Distance is the rated distance (this can be short, intermediate, long).
Media is the type of fiber or copper cable.
Transmitter is the type of optical or electrical transmitter.

Media Connectors

A connector is the part of a cable that plugs into a port or interface to connect one device to another. Most connectors are either male (containing one or more exposed pins) or female (containing holes in which the male connector can be inserted).

Dell SAN devices support DB-9, HSSDC (High-Speed Serial Data Connector), and SC connectors.

Media type and description

DB-9 DB-9 connector The DB-9 cable connector is a serial interface with nine pins.

HSSDC HSSDC connector The High-Speed Serial Data Connector (HSSDC) provides better impedance control over the DB-9 connectors.

SC SC connector The Subscriber Connector (SC) is used with optical cables. Long wave and short wave cables are not interchangeable.

Color Coding

The cables used in a Dell SAN are color-coded by their specific function. For example, copper cables with HSSDC connectors at both ends are sheathed in blue material and thus called "blue cables". Generally, a sticker will be attached to the cable indicating its color code.

Cable colors

"Red" Cable

An HSSDC to DB-9 copper cable.
Cable lengths of 1.5m, 3m, 6m, or 12m.
Commonly used for: connecting a PowerVault 650F to either a server or a switch.

"Blue" Cable

An HSSDC to HSSDC copper cable.
Cable lengths of 2m, 6m, or 12m.
Commonly used for: connecting a server to a switch; cascading two switches.

"Green" Cables

A DB-9 to DB-9 copper cable.
Cable lengths of 2 ft, 10 ft, .3m, or 1.5m.
Commonly used for: connecting a PowerVault 650F to a PowerVault 630F DAE (disk-array enclosure), or connecting two 630Fs together.

"Orange" Cable

An SC to SC optical multimode short-wave cable.
Cable lengths ranging from 2 ft up to 500m.
Commonly used for: connecting a Fibre Channel-to-SCSI bridge to either a server or a Fibre Channel Switch; connecting a server to a FC switch; cascading two FC switches.

"Purple" Cable

An SC to SC optical single mode long-wave cable.
Cable lengths of up to 10km.
Commonly used for: connecting a Fibre Channel-to-SCSI bridge to either a server or switch; or, cascading two FC-to-SCSI switches.

NOTE: Single-mode fiber can carry a signal for greater distances than multi-mode fiber because there is no chromatic dispersion (interference caused by variable absorption and reflection as light waves interact with the sheath around the optical fiber).