Centralised vs. Distributed Control Systems
Centralised Control Systems
Centralised control systems rely on a single central computer to manage all processing and decision-making.
Definition
Centralised control system
A control system that relies on a single central computer to manage all processing and decision-making
This architecture offers several advantages:
- Simplified Management: All data and processes are handled in one location, making it easier to monitor and control.
- Cost-Effective: Client devices require minimal hardware since the central system performs all computations.
- Enhanced Security: Data is stored centrally, reducing the risk of unauthorised access across multiple locations.
- Efficient Backup: With all resources in one place, backing up data is straightforward and less resource-intensive.
Note
Centralised systems are often used in environments where reliability and control are paramount, such as banking systems or large-scale enterprise networks.
In contrast, the disadvantages are:
- Single Point of Failure: If the central system or its connection fails, the entire network can become inoperative.
- Scalability Challenges: Expanding the system requires a significant investment in the central infrastructure.
- Network Dependency: Client devices must maintain a stable connection to the central system, which can be a bottleneck.
Note
- A common misconception is that centralised systems are always more secure.
- While data is stored in one location, a breach of the central system can compromise the entire network.
Distributed Control Systems
Definition
Distributed control system
A control system that spreads processing and decision-making across multiple independent nodes
Each node can operate autonomously, offering several advantages:
- Resilience: If one node fails, others can continue to function, ensuring system stability.
- Scalability: New nodes can be added without disrupting the existing system.
- Reduced Latency: Processing is done locally, minimising delays caused by network communication.
Hint
Distributed systems are ideal for applications such as smart grids or autonomous vehicles, where real-time decision-making is crucial.
And disadvantages such as:
- Higher Costs: Each node requires its own hardware and software, resulting in increased initial expenses.
- Complex Management: Coordinating multiple nodes can be challenging, particularly in terms of maintaining data consistency and ensuring security.
- Backup Complexity: Distributed data requires more resources for synchronisation and backup.
Common Mistake
- It's a common mistake to assume that distributed systems are always more reliable.
- While they offer redundancy, poor coordination between nodes can lead to data inconsistencies or system failures.
TL,DR: Comparing Centralised and Distributed Systems
| Aspect | Centralised Systems | Distributed Systems |
|---|---|---|
| Architecture | Single central computer | Multiple independent nodes |
| Scalability | Limited by central system capacity | Easily expandable by adding nodes |
| Resilience | Single point of failure | Redundant, with nodes operating independently |
| Cost | Lower initial cost for clients | Higher initial cost due to distributed hardware |
| Security | Easier to secure centrally stored data | More challenging to secure multiple nodes |
| Latency | Higher, due to network dependency | Lower, with local processing |
Example
- Imagine a centralised system as a single traffic control tower managing an entire city's traffic lights.
- If the tower fails, chaos ensues.
- In contrast, a distributed system is like each intersection having its own controller, ensuring traffic flows smoothly even if one controller malfunctions.
Example
- Imagine, in the case of smart grids, a single control centre manages power distribution, optimising efficiency but risking widespread outages if the centre fails.
- In contrast, in the case of a distributed system, local nodes adjust power distribution based on real-time data, enhancing resilience and reducing downtime.
Ethical and Practical Considerations
- Data Privacy: Centralised systems may offer better data protection, but a breach can have widespread consequences. Distributed systems require robust encryption and access controls across all nodes.
- Resource Allocation: Distributed systems can be more energy-efficient by processing data locally, reducing the need for constant communication with a central server.
- Scalability vs. Cost: Organisations must balance the scalability of distributed systems with the higher initial costs of hardware and software.
Hint
Understanding the differences between centralised and distributed control systems is crucial for designing efficient, resilient, and scalable solutions. As you explore these architectures, consider the following:
- Context Matters: The choice between centralised and distributed systems depends on the specific requirements of the application, such as scalability, resilience, and cost.
- Balance Trade-Offs: Each architecture has its strengths and weaknesses. Effective system design involves striking a balance between these trade-offs to meet the needs of both users and the environment.
- Think Critically: When evaluating control systems, consider not only their technical capabilities but also their ethical and social implications.
Self review
- What are the key differences between centralised and distributed control systems?
- How do distributed systems handle failures compared to centralised systems?
- Can you think of a scenario where a centralised system might be more appropriate than a distributed one?
Theory of Knowledge
- How do centralised and distributed systems reflect different approaches to problem-solving in computer science?
- What ethical considerations arise when choosing one architecture over the other?
