1. What is Service Level Availability?

Service Level Availability measures the percentage of time a service is operational and accessible to users. It's a critical metric for evaluating service reliability and performance in IT systems, networks, and online services.

2. How Does the Calculator Work?

The calculator uses the availability formula:

Where:

• \( \text{Total Time} \) — Total monitoring period in hours
• \( \text{Downtime} \) — Total time the service was unavailable in hours

Explanation: The formula calculates the proportion of time the service was available relative to the total monitoring period, expressed as a percentage.

3. Importance of Availability Calculation

Details: Availability measurement is crucial for service level agreements (SLAs), capacity planning, infrastructure monitoring, and ensuring business continuity. High availability percentages indicate reliable service delivery.

4. Using the Calculator

Tips: Enter total monitoring time and downtime in hours. Both values must be positive numbers, and downtime cannot exceed total time. The result shows availability as a percentage.

5. Frequently Asked Questions (FAQ)

Q1: What is considered good availability?
A: For critical services, 99.9% ("three nines") or higher is typically expected. 99.99% ("four nines") allows only 52.6 minutes of downtime per year.

Q2: How is downtime measured?
A: Downtime includes all periods when the service is completely unavailable or performing below acceptable thresholds as defined in SLAs.

Q3: Does planned maintenance count as downtime?
A: This depends on SLA definitions. Some agreements exclude planned maintenance from downtime calculations, while others include it.

Q4: What's the difference between availability and uptime?
A: Uptime refers to the time a system is operational, while availability measures the percentage of time a service is accessible and functioning properly.

Q5: How often should availability be measured?
A: Continuous monitoring is ideal, but availability is typically calculated over specific periods (daily, weekly, monthly) for reporting and SLA compliance.