High availability
HA is a concept and practice that hasn’t changed even today. A highly available system provides an agreed level of uptime or SLA. HA is the ability to withstand planned and unplanned outages and to provide continuous processing of business-critical applications. Enterprises have always measured availability or uptime in terms of 9s. In the past, most enterprises considered achieving five nines or even four nines nirvana. According to Dunn and Bradstreet, 59% of Fortune 500 companies still experience a minimum of 1.6 hours of downtime per week. And according to TechChannel, based on the ITIC survey for 2021, the average cost of an hour of downtime on average is over $300,000. Are four nines – that is, 52.56 minutes of downtime per year – even achievable? Take a look at the following table for clarification about the number of 9s:
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Level of Availability |
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