Understanding Compaq StorageWorks RAID Array 4000 and Infrastructure Cabling
Understanding Compaq StorageWorks RAID Array 4000 and Infrastructure Cabling 5
ECG02030699A
Distance Limitations
Two factors that can limit the distance between the components are:
1. The data transmission rate—as shown in Table 1, the distance between the components of
each fiber type tends to decrease as the data transmission rate increases.
2. The degree of attenuation—attenuation is the reduction of the signal strength during
transmission from point to point. In this case, it is the light passing through the optic media.
The number of connectors and splices used to connect components affects the distance that
can exist between components.
Table 1. Data transmission rates and distance capabilities of fiber types
Transmission Rate
Supported by
Compaq
62.5-micron 50-micron 9-micron
100 MB/s
5
Yes 300 m 500 m 10 km
200 MB/s Future
6
150 m 300 m 2 km
400 MB/s Future 90 m 150 m 2 km
Formulas used to calculate the distance limitations are based on the data transmission rates and
the degree of attenuation. A company that provides fiber products and installation and testing
services can help determine distance capabilities and limitations for a particular installation. See
Acknowledgements and References later in this document.
Connection Components
To build a storage system that uses fibre channel technology, it is necessary to understand the use
and function of, hubs, gigabit interface converters (GBICs), and fibre channel cables and
connectors.
• Hubs allow of different GBIC types to be mixed so there can be different cable types within a
fibre channel topology. Hubs use port bypass circuitry to keep a fibre channel loop topology
intact.
• GBICs convert electrical signals to optical signals and optical signals to electrical signals at
the point where fiber cables connect to copper-wired components (hubs, controller cards, and
host adapters).
• Fibre channel cables and connectors join system components and connect to infrastructure
cabling.
5
Megabytes per second
6
A 200 MB/s transmission rate may be passed over in favor of a 400 MB/s transmission rate.