High Availability

• Aims to keep services continuously available by minimizing downtime
• Achieved through load balancing, clustering, redundancy, and multi-cloud strategies

Uptime and Availability Standards

• Uptime — The time a system remains online, typically expressed as a percentage
• Five nines — Refers to 99.999% uptime, allowing only about 5 minutes of downtime per year
• Six nines — Refers to 99.9999% uptime, allows just 31 seconds of downtime per year

Load balancing

• Distributes workloads across multiple resources
• Optimizes resource use, throughput, and response time
• Prevents overloading of any single resource
• Incoming requests are directed to capable servers

Clustering

• Uses multiple computers, storage devices, and network connections as a single system
• Provides high availability, reliability, and scalability
• Ensures continuity of service even in case of hardware failure
• Can be combined with load balancing for robust solutions

Redundancy

• Involves duplicating critical components to increase system reliability
• Prevents single points of failure in systems