ITPEC FE Morning October 2019 Question 56
IT services are provided under the following conditions in the SLA. What is the maximum number of hours of downtime in a month that can satisfy the SLA?
[Conditions of the SLA]
The number of business days per month is 30.
The service hours are from 7 AM to 11PM o'clock on a business day.
The required availability is 99% or more.
Other required time, such as maintenance time, can be ignored.
Explanation
4.8 hours — the 1% allowance applies to the scheduled service hours, not to every hour of the month.
- •Service hours per day: 7 AM to 11 PM = 16 hours
- •Service hours per month: 16 × 30 = 480 hours
- •Allowed downtime: 480 × (1 − 0.99) = 480 × 0.01 = 4.8 hours
Answer (c)
Why not others:
- •(a) 1.2 — 4 × 30 × 0.01: a 4-hour day, as if the service ended at 11 AM instead of 11 PM
- •(b) 3.0 — would need 300 service hours, 10 a day, which no reading of 7 AM to 11 PM gives
- •(d) 7.2 — 24 × 30 × 0.01: counts all 720 hours of the month, including the 8 hours a day when no service is offered
Key rule: SLA availability is measured over the agreed service hours only, so the downtime allowance is service hours × (1 − agreed availability).
Service Management · AI-written, may contain errors
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