Fri Apr 8 06:47:17 PDT 2016
Redundancy: Redundant facility distance: How far apart are redundant data centers and people to assure continuity?
Option 1: There is no distance requirement.
Option 2: Use a backup facility at least 5 miles away.
Option 3: Use a backup facility in another city.
Option 4: Use a backup facility at least 250 miles away.
Option 5: Use a backup facility on another continent.
There is no distance requirement.
When no redundant data center or other related facility is
required, there is no associated distance requirement.
Use a backup facility at least 5 miles away.
For very small localized businesses, if the owner survives, a set
of backups that can be recovered within days to weeks and the ability
to purchase new hardware is adequate. Redundant data centers are not a
requirement at all. To the extent that there is redundancy, most
protection is against single facility failures such as the main place
of business burning down or some service outage. Redundancy may be
limited to a backup tape taken home with the owner at night or every
Use a backup facility in another city.
For strictly regional companies, city to city redundancy is
called for unless the enterprise is single facility or very limited in
geographical scope. By spreading across cities, local government
failures, telecommunications outages, common energy and infrastructure
failures, most riots and fires, many tornadoes, hurricanes, earth
movements, most floods, and many other similar events can be survived,
Care must be taken to assure that commonalities are avoided in each of
the interdependent areas so that business continuity is assured. For
example, placing all data centers along coast lines could be subject
to common mode failures associated with increases in sea level. Cost
differences are typically very small for assuring proper
infrastructure redundancy, but expertise is needed to verify this
Use a backup facility at least 250 miles away.
Many enterprises operate within only one continent or country, or
substantially do so in terms of their need for information
technologies associated with business continuity. In these cases,
distance becomes an issue when regional events take place. In the US,
for example, there are hurricanes that effect one region, earthquakes
in another region, floods and storms in another region, winter related
infrastructure failures in another region, and so forth. If the
enterprise exists only within a certain region, then it doesn't
particularly help to have redundant data centers elsewhere because
they will be of little use when the rest of the business does not
operate. The exception is the large enterprise that is dominant in a
region but has enough diversity in operations to continue even when
that region is hit by a regional event. Enterprises that cross regions
usually have substantial facilities in more than one region, and these
are often, but not always, ideal locations for redundant data centers.
Use a backup facility on another continent.
Copyright(c) Fred Cohen, 1988-2015 - All Rights Reserved
Distance requirements for backup facilities are driven entirely
by scenarios that can lead to simultaneous loss. These in turn are
threat driven. If an enterprise has to be able to survive limited
nuclear attack, government insurrections, regional and world wars, and
comet strikes that don't end all human life, transcontinental
diversity is a necessity. There are many global multinationals that
have this requirement and the efficiency gained by reducing this sort
of redundancy does not justify the collapse of the business under
conditions that, in the case of wars and governmental changes, happen