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Backup
sites for computer systems, control centers, and equipment can support the high
availability requirements for power system operations. These backup site
scenarios can range from minimal to complete:
· Critical system
files and databases can be stored off-line and off-site so that they can be
used in case of the destruction of the on-site files through fire, earthquake,
theft, or other catastrophe
· Critical system
files and databases can be stored off-site, but remain on-line and
interconnected with the main system so that they can be used as normal backup
during routine maintenance or short-term failures. This scenario implies that
communications systems have been installed which permit the users to remain at
their normal site, but just run the systems at the backup site.
· “Bunker sites”
can be created which contain primarily user interfaces connected to the main
systems over communications systems. These bunker sites can be used by the
users if the normal site is not available (e.g. evacuation has been ordered).
These sites can be close by or far away, with the time for users to travel
between the sites a major consideration in deciding this distance.
· Exchanging
backup sites with a neighbor, so that duplicates of their systems are at your
site, and duplicates of your systems are at their sites. This can be less
costly than renting space from a commercial backup site.
· Including each
other’s system software on each other’s systems, so that if one system fails or
the users cannot access it, the other system is available to run the first
systems software. This is usually only practical for organizations that are
tightly coupled.
· Mostly complete
system at the backup site.
· Complete backup
site that is a total mirror of the original site.
The
required availability and the financial capabilities are the main drivers of
which alternative to choose. In addition, the type of “failover” from one site
to the other can vary, depending upon the degree of automation and
communications support. Failover can range from manual to completely automated,
with failover times ranging from weeks to milliseconds.
Keywords:
Backup, sites, failover
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