Section 14.123 High Availability

Question 1

High Availability

Answer 1

Aims to keep services continuously available by minimising downtime

● Achieved through load balancing, clustering, redundancy, and multi-cloud strategies

Question 2

Uptime

Answer 2

The time a system remains online, typically expressed as a percentage

Question 3

Five nines

Answer 3

Refers to 99.999% uptime, allowing only about 5 minutes of downtime per year

Question 4

Some cloud based networks

Six nines

Answer 4

Refers to 99.9999% uptime, allows just 31 seconds of downtime per year

Question 5

How to maintain uptime

Load Balancing

Answer 5

Distributes workloads across multiple resources

■ Optimises resource use, throughput, and response time
■ Prevents overloading of any single resource
■ Incoming requests are directed to capable servers

Think of load balancing like traffic management. Imagine a toll booth with multiple lanes. The goal is to distribute cars (requests) to the lanes (servers) so no single lane gets backed up. If one lane closes, traffic may slow down unless there’s a backup plan

Question 6

How to maintain uptime

Clustering

Answer 6

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

Clustering is like a relay team in a race. If one runner (node) stumbles, another immediately takes the baton and keeps the team moving. They work closely together, sharing responsibility to ensure the race (system) continues without interruption.

Question 7

How to maintain uptime

Redundancy

Answer 7

Involves duplicating critical components to increase system reliability

■ Redundancy can be implemented by adding multiple:
● Power supplies
● Network connections
● Servers
● Software services
● Service providers

Prevents single points of failure in systems e.g Redundant power supplies

Question 7

Multi-Cloud Approach

Answer 7

Distributes data, applications, and services across multiple cloud providers

■ Mitigates the risk of a single point of failure
■ Offers flexibility for cost optimisation
■ Aids in avoiding vendor lock-in
■ Requires proper data management, unified threat management, and consistent policy enforcement for security and compliance

Question 8

Strategic Planning

Answer 8

Design a robust system architecture to achieve high availability

■ Utilise load balancing, clustering, redundancy, and multi-cloud approaches
■ Proactive measures reduce the risk of service disruptions and downtime costs
■ Safeguard organisational continuity and reliability in a competitive environment