SLA Policy Template
SLA Policy review every 6 months - last [date]
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INTRODUCTION
To Set out the needs and requirements of the business with regards to uptime, error allowance and performance of systems commensurate with business needs.
COMMON LANGUAGE
SLA - Service level agreements
SLO - Service level objectives can give a low-noise signal as to the overall health of services.
SLI - Service level indicators is a quantitative measure of some aspect of the service. Typically this could be latency or availability.
“Three 9s” refers to 99.9% uptime, this allows an error budget of 1 minus the SLO or SLA. For example three 9s would allow 1000 errors from 100,000 requests to an API without breaching contractual agreements.
“Four 9s” refers to 99.99% uptime, this allows an error budget of 1 minus the SLO or SLA. For example four 9s would allow 100 errors from 100,000 requests to an API without breaching contractual agreements.
Error Budget - An error budget is the maximum amount of time that a technical system can fail without contractual consequences.
Compliance Periods - The period of time of which the SLO/SLA is measured. e.g. a rolling 30 day period, or rolling 12 month period, or a fixed quarter.
AGREED SERVICE LEVELS
- SLO
- Latency - TBD
- Availability - Uptime of Three nines (8.77 hours error budget) per 12 month rolling period.
APPENDIX
| Availability% | Downtime per year | Downtime per quarter | Downtime per month | Downtime per week | Downtime per day (24 hours) |
|---|---|---|---|---|---|
| 90% (“one nine”) | 36.53 days | 9.13 days | 73.05 hours | 16.80 hours | 2.40 hours |
| 95% (“one nine five”) | 18.26 days | 4.56 days | 36.53 hours | 8.40 hours | 1.20 hours |
| 99% (“two nines”) | 3.65 days | 21.9 hours | 7.31 hours | 1.68 hours | 14.40 minutes |
| 99.5% (“two nines five”) | 1.83 days | 10.98 hours | 3.65 hours | 50.40 minutes | 7.20 minutes |
| 99.9% (“three nines”) | 8.77 hours | 2.19 hours | 43.83 minutes | 10.08 minutes | 1.44 minutes |
| 99.99% (“four nines”) | 52.60 minutes | 13.15 minutes | 4.38 minutes | 1.01 minutes | 8.64 seconds |
| 99.999% (“five nines”) | 5.26 minutes | 1.31 minutes | 26.30 seconds | 6.05 seconds | 864.00 Milliseconds |