 | Measurement interval is a key to extended outages
 | Assume 99.5% availability
 | If one month, allows a failure within the month of > 3.5 hours
 | If one day, less than 8 minutes per day
| |  | Go for the nines!
 | 99.95% allows 22 minutes per month outage
 | 99.995 allows about 2 minutes per month
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