Redundancy and fault tolerance in HLD - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is redundancy in system design?

Redundancy means having extra components or systems that can take over if the main ones fail. It helps keep the system working without interruption.

beginner

Define fault tolerance in simple terms.

Fault tolerance is the ability of a system to keep working even when some parts fail. It prevents total system failure by handling errors smoothly.

intermediate

Why is redundancy important for fault tolerance?

Redundancy provides backup parts or systems. Fault tolerance uses these backups to continue working when failures happen, making the system reliable.

intermediate

Name two common types of redundancy used in system design.

1. Hardware redundancy: extra physical devices like servers or disks.<br>2. Data redundancy: copies of data stored in multiple places.

advanced

What is the difference between active and passive redundancy?

Active redundancy means backup components run alongside the main ones all the time.<br>Passive redundancy means backups only start working when the main components fail.

What does fault tolerance help a system do?

A Reduce data storage

B Run faster under load

C Use less power

D Keep working despite failures

Fault tolerance means the system continues working even if some parts fail.

Which of these is an example of hardware redundancy?

A Using a faster CPU

B Compressing data to save space

C Multiple servers running the same service

D Encrypting data for security

Hardware redundancy involves extra physical devices like servers to provide backup.

Passive redundancy means backups:

A Run all the time alongside main components

B Only activate when main components fail

C Are never used

D Are faster than main components

Passive redundancy backups start working only when the main parts fail.

Which term means having extra copies of data stored in different places?

A Data redundancy

B Load balancing

C Caching

D Sharding

Data redundancy means storing copies of data in multiple locations for safety.

What is the main goal of redundancy in system design?

A To improve system reliability

B To reduce system cost

C To increase system complexity

D To slow down system response

Redundancy aims to improve reliability by providing backups.

Explain how redundancy and fault tolerance work together to keep a system reliable.

Think about backups and how the system keeps running when parts fail.

Describe the difference between active and passive redundancy with examples.

Focus on when backups are running or activated.