Every company faces critical hours when system downtime is unwelcome-whether
it's planned or unplanned. One company's important hours might only be from 9-to-5, while for another it's 24x7. Increasingly, shops that were able to accommodate some periods of downtime for backups and system maintenance are finding that this window is quickly shrinking (or has disappeared altogether) because of increased system demands—especially from global and online business.

Because of the need to keep systems available for increasing amounts of time, companies are realizing that a system failure or a site disaster would create an enormous disruption and expense...