Characteristics of Distributed Systems

Question 1

You are given a prompt, and you ask enough questions to thoroughly understand the functionality needed. Now ask which qualities of the system should be prioritized? These are the 5:

Answer 1

1. Scalability
2. Reliability
3. Availability
4. Efficiency
5. Manageability

Question 2

1. Scalability

Answer 2

• capability of a system to grow and
  manage increased demand, while
  mitigating performance loss
• reasons a system may have to scale:
  
  • increased data volume
  • increased transaction volume
• horizontal vs. vertical scaling

Question 3

2. Reliability

Answer 3

• probability a system will fail
• needs to keep delivering its services
  even if some components fail.
• achievable by redundancy of both the
  software components and data
• highly reliable –> highly available

Question 4

3. Availability

Answer 4

• time a system remains functional
• takes into account maintainability, repair
  times and spares availability.
• highly reliable –> highly available
• can be very available but not reliable, if
  repair times are minimal and theres
  available spares of data and
  components

Question 5

4. Efficiency

Answer 5

• good measures are typically latency and
  throughput delivered in a given time.
• this is typically relative as there are
  many impacting aspects.

Question 6

5. Manageability

Answer 6

• simplicity and speed with which a
  system can be repaired or maintained.
• low manageability –> decreased
  availability, thus reliability (most likely) .

Question 7

Horizontal Scaling

Answer 7

• associated with NOSQL
• add more servers to the pool or cloud
  coverage
• easier to scale dynamically
• more cost effective than vertical scaling
• Cassandra, MongoDB

Question 8

Vertical Scaling

Answer 8

• Associated with SQL
• add more power to existing server
  (CPU, RAM, Storage).
• limited by server capacity
• involves downtime
• less cost effective
• MySQL allows for easy way to switch
  from machines but still has downtime