Glossary
Uptime (and the nines)
Uptime is the percentage of time a service is available and operational. “The nines” is shorthand for the digits of precision in that percentage, from 99% (two nines) to 99.999% (five nines).
General definition
Uptime is calculated as the ratio of available time to total time in a measurement window, expressed as a percentage. Each additional nine reduces the allowed downtime by roughly a factor of ten:
- 99% (two nines): ~87.6 hours of allowed downtime per year
- 99.9% (three nines): ~8.76 hours per year
- 99.95%: ~4.38 hours per year
- 99.99% (four nines): ~52.6 minutes per year
- 99.999% (five nines): ~5.26 minutes per year
Uptime targets are codified in SLAs as commitments with financial penalties for breach, and in SLOs as internal engineering targets. Achieving higher nines requires high-availability architecture, redundant components, and well-tested disaster-recovery procedures.
In the Ethora ecosystem
On a cloud-hosted Ethora plan, the platform’s uptime commitment is the provider’s responsibility and is stated in the SLA. The engineering team maintains the redundant infrastructure, applies patches, and handles failovers. Customers receive credits if the SLA is breached but cannot independently control the redundancy architecture.
With a dedicated or self-hosted chat server, you set your own uptime target and are responsible for the architecture that delivers it. Ethora can deploy into a multi-node, multi-region configuration designed for your target SLO, and under a support contract the team co-owns the uptime obligation with you. For healthcare and financial-services buyers who must meet regulatory availability requirements and demonstrate control to auditors, owning the uptime architecture is a compliance advantage. See pricing for dedicated support tiers.
