Cloud and System Architecture Terminology - Answers

 

1. How do you define cloud architecture? - Applying cloud characteristics to a solution that uses cloud services and features 
2. What does serverless mean? Way to build and run applications and services without thinking about servers. It is the architecture of the cloud. You shift more operational responsibilities to AWS , and you focus on agility and innovation. You do not worry about provisioning, patching, OS maintenance and capacity provisioning of servers.
3. How do you define "reliability"? Measure of system's ability to provide functionality when desired by the user
4. How do you measure reliability? In what units? Hours
5. How do you calculate and measure reliability? Using Mean time between failures (MTBF) over provided period of time, most commonly 1 year . MTBF = (Total time in service)  / (Number of failures) 
6. How do you define availability? % of time your system is operating normally 
7. How do you measure availability? In what units? In percentages, commonly number of 9s. 5 9s means 99.999%.
8. How do you calculate availability? Availability = Normal operational time / Total time
9. What is a highly available system? A system that can whit stand some measure of degradation while still remaining available with minimal downtime and minimal human intervention
10. How do you define "fault tolerance" ? - Building redundancy and ability to remain operational
11. How do you define scalability? Ability to accommodate increases in capacity needs without changing design
12. How do you define recoverability? Ability to restore service quickly and without loss of data in case of disaster
13. What is the relationship between availability, recoverability, fault tolerance and scalability? Recoverability, fault tolerance and scalability all influence availability.