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For many organizations, a loss of service is just as devastating as a loss of information. The odds of service interruption or information loss decrease significantly if no single points of failure exist. Some interesting and powerful technologies exist that can keep mission-critical services available even in the face of a catastrophic disaster.

Key Points

  • Recovering from a network catastrophe takes time.
  • Sooner or later, a major system failure will happen.
  • A truly redundant information system contains no single points of failure.
  • Maintaining high availability becomes more difficult and more expensive as systems increase in size.


Ensuring availability is a challenge for any organization, large or small. There is much more to ensuring availability than making sure data is backed up. The following chapters cover a variety of methods to help keep data ready and waiting at all times:

  • RAID introduces technique for using multiple synchronized hard drives to increase performance and/or reliability.

  • Clustering describes a technology that allows a system to remain operational if its hardware or software fails by replicating its running processes on a simultaneous system in real time.

  • Backup Systems actually perform two functions, copying critical data to another location and enabling the swift and painless recovery of the backed up data.

  • Distributed Computing (web bonus) is used to obtain unprecedented power, availability and capacity by getting many machines to work together on a problem.

  • Rollout Systems (web bonus) explores tools that enable updates or installations to occur over networks, to many nodes at the same time.