System Access and Availability
System access and availability refers to when users—including personnel and customers—need a system or service, which is an important consideration. Some systems must be operational 99.999 percent of the time. Other systems must be operational only during business hours, such as between 8:00 a.m. and 5:00 p.m., Monday through Friday.
NOTE
Five nines, or 99.999 percent uptime, is sometimes needed for certain services, which equates to about 5.256 minutes of downtime a year. The calculation is 60 minutes × 24 hours × 365 days × .00001.
Five nines, or 99.999 percent uptime, can be achieved. FIGURE 7-1 shows a ...
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