Server Availability & SLA Uptime

Allowable downtime breakdown for 99% to 99.999% (Five Nines), planned maintenance, MTBF and MTTR.

Common SLA targets:

Custom SLA (%)

Planned maintenance (hours / month)

MTBF: mean time between failures (hours)

MTTR: mean time to repair (hours)

Maximum allowed downtime (downtime budget)

99.9% Uptime

Per year (365.25 days)

8h 45m 58s

Per month (30.4 days)

43m 50s

Per week (7 days)

10m 5s

Per day (24 hours)

1m 26s

Intrinsic availability from MTBF and MTTR:

Formula: MTBF / (MTBF + MTTR)

99.931%

Convert a target availability percentage into a downtime allowance per period. Compare service level targets and reliability indicators.

Over a 30-day month, 99.9% uptime permits approximately 43.2 minutes of downtime. The exact allowance depends on the contractual measurement period.

A contractual SLA may exclude maintenance or apply specific measurement rules. Check the contract and reporting window before relying on an estimate.

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