Within the Cloud: Technical Concepts of Cloud Computing - Deploying and Managing a Cloud Infrastructure - page 59

each). The heat generated would be tremendous, and so it follows that the cooling systems
for the whole floor area and for each rack would have to be on par to keep the temperature
at manageable levels, preventing overheating even in times of extreme processing load.
The industry ad hoc standard for calculating cooling requirements is to have one British
thermal unit (BTU) of cooling for every three kilovolt-amps (kVA) power requirements. And
cooling is usually described in tons, with one ton of air having 12,000 BTUs of cooling.
Another consideration is the equilibrium of the cooling for HVAC systems. The atmo-
sphere within the center must maintain a good mixture of levels, keeping in mind operating
temperature as well as operator comfort. Nicely cooled equipment is good, but the environ-
ment must be comfortable for the operators to work within the premises. Humidity levels
must also be monitored as high levels would cause condensation and equipment corrosion
while low levels facilitate occurrences of electrostatic discharge (ESD).

Network Connectivity and Security
All that super computing power would go to waste if you cannot direct it to your users.
The main objective of a data center is to house computer equipment, and it needs network
connectivity to have any purpose at all. The network must be well designed with future
growth in mind, so an upgrade path must be considered in the design.
Data cables would consist of a mixture of fiber optics and Cat 5e or Cat 6 rated cables, but
quality of connectivity will depend on the type of equipment being used, which also depends
on the applications that the center needs to offer. The position and distribution of network
equipment needs to be well thought out, especially in large data centers where the distances
can easily go beyond recommended cable lengths for device interconnectivity. The data center's
orientation to the building's telecommunications equipment should be considered, and any
equipment meant for external communication should be placed as close to the Telco's closest
ingress into the data center as possible to reduce latency.
But the main issues in planning network connectivity involve capacity and redundancy .
Capacity is the total bandwidth in both directions of your data center, while redundancy
relates to keeping the connection alive by selecting external connectivity providers that
offer high redundancy or by employing multiple service providers. Table 3.1 shows different
leased lines that are usually offered by network providers.

TABLE 3.1 Types of leased lines

Leased Line Capacity

T1/DS-1 1.544 Mbps

T3/DS-3 44.75 Mbps

OC-3 155.52 Mbps