🌩️ Parallel and Distributed Systems

🖥️ 1. What is a Parallel System?

📌 Definition

A Parallel System is a computing system where multiple processors (CPUs) work together simultaneously to solve a single problem.

👉 In simple words: Breaking one big task into smaller parts and solving them at the same time on one system

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⚙️ How Parallel Systems Work (Step-by-Step)

Task → Split into Parts → Processors (CPU1, CPU2, CPU3) → Combine Results

🧠 Steps:

1. A large task is divided into smaller tasks
2. Each processor handles one part
3. All parts are executed at the same time
4. Results are combined

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📦 Example

• Image processing (splitting image into parts)
• Scientific calculations
• Video rendering

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🎯 Key Features of Parallel Systems ⭐

✔ Multiple processors in one machine ✔ Shared memory ✔ High speed ✔ Tight coupling (closely connected components)

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🌐 2. What is a Distributed System?

📌 Definition

A Distributed System is a collection of multiple independent computers (nodes) connected through a network that work together as a single system.

👉 In simple words: Many computers in different locations working together

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⚙️ How Distributed Systems Work (Step-by-Step)

User → Network → Computer 1
               → Computer 2
               → Computer 3 → Results Combined

🧠 Steps:

1. Task is divided into parts
2. Each part is sent to different machines
3. Machines process independently
4. Results are combined

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📦 Example

• Cloud computing systems
• Web services
• Online banking systems

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🎯 Key Features of Distributed Systems ⭐

✔ Multiple independent computers ✔ Connected via network ✔ No shared memory ✔ Loosely coupled

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⚖️ 3. Parallel vs Distributed Systems (VERY IMPORTANT ⭐)

Feature	Parallel System	Distributed System
Definition	Multiple processors in one system	Multiple computers connected via network
Location	Same machine	Different locations
Memory	Shared memory	Separate memory
Coupling	Tight	Loose
Communication	Very fast	Slower (network-based)
Example	Multi-core CPU	Cloud computing

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🔗 4. Relationship with Cloud Computing

☁️ Cloud uses Distributed Systems

👉 Cloud computing is mainly based on distributed systems

✔ Data stored across many servers ✔ Tasks processed in different locations

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🧠 Combined Use:

• Parallel processing inside servers
• Distributed processing across data centers

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🧩 5. Advantages of Parallel Systems

🟢 Benefits

✔ Faster execution ✔ Efficient resource usage ✔ Handles complex problems

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🧩 6. Advantages of Distributed Systems

🟢 Benefits

✔ Scalability (add more machines) ⭐ ✔ Reliability (failure of one node doesn’t stop system) ✔ Resource sharing ✔ Geographic distribution

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⚠️ 7. Challenges

🔴 Parallel System Challenges

• Synchronization issues
• Deadlocks
• Complex programming

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🔴 Distributed System Challenges ⭐

• Network failures
• Data consistency
• Security issues
• Latency (delay)

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📊 8. Diagram: Combined View

          Cloud System
               |
     ---------------------
     |                   |
 Parallel Processing   Distributed Systems
 (Inside server)      (Across servers)

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📝 9. Important Exam Questions ⭐

👉 Define parallel system 👉 Define distributed system 👉 Difference between parallel and distributed systems 👉 Advantages of distributed systems 👉 Role in cloud computing

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📊 10. Final Summary Table (Quick Revision)

Topic	Parallel System	Distributed System
Basic Idea	One system, many processors	Many systems connected
Speed	Very fast	Depends on network
Memory	Shared	Separate
Location	Same place	Different places
Scalability	Limited	High
Reliability	Moderate	High
Example	Multi-core CPU	Cloud computing

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🧠 Final Revision Tips

✔ Remember key difference: same machine vs multiple machines ✔ Learn shared vs separate memory ✔ Understand cloud = distributed system ✔ Use examples in answers

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