Page 49 - Asterisk™: The Future of Telephony

Computer power supplies
The power supply you select for your system will play a vital role in the stability of the
entire platform. Asterisk is not a particularly power-hungry application, but anything
relating to multimedia (whether it be telephony, professional audio, video, or the like)
is generally sensitive to power quality.
This oft-neglected component can turn an otherwise top-quality system into a poor
performer. By the same token, a top-notch power supply might enable an otherwise
cheap PC to perform like a champ.
The power supplied to a system must provide not only the energy the system needs to
perform its tasks but also stable, clean signal lines for all of the voltages your system
expects from it.
Spend the money and get a top-notch power supply (gamers are pretty passionate about
this sort of thing, so there are lots of choices out there).

Redundant power supplies
In a carrier-grade or high-availability environment, it is common to deploy servers that
use a redundant power supply. Essentially, this involves two completely independent
power supplies, either one of which is capable of meeting the power requirements of
the system.
If this is important to you, keep in mind that best practices suggest that to be properly
redundant, these power supplies should be connected to completely independent un-
interruptible power supplies (UPSes) that are in turn fed by totally separate electrical
circuits. In truly mission-critical environments (such as hospitals), even the main elec-
trical feeds into the building are redundant, and diesel-powered generators are on-site
to generate electricity during extended power failures (such as the one that hit North-
eastern North America on August 15, 2003).

Environment

Your system’s environment consists of all of those factors that are not actually part of
the server itself but nevertheless play a crucial role in the reliability and quality that can
be expected from the system. Electrical supplies, room temperature and humidity,
sources of interference, and security are all factors that should be contemplated.

Power Conditioning and Uninterruptible Power Supplies

When selecting the power sources for your system, consideration should be given not
only to the amount of power the system will use, but also to the manner in which this
power is delivered.

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