Slave Master


The term “Master/Slave” refers to a communication model in computer systems, where one device (master) controls and coordinates the operation of other devices (slaves). The master device initiates communication and data requests while the slave devices respond and follow the master’s instructions. This term is becoming outdated and is being replaced with more inclusive terms like primary/secondary or leader/follower.

Key Takeaways

  1. The master/slave terminology refers to a model of communication and control in which one device (the master) has authority over and is responsible for controlling the actions of other devices (slaves).
  2. Master/slave relationships can be found in various technological contexts, such as database replication, distributed computing, and peripheral hardware electronics, where the main device (master) coordinates and manages its interaction with subordinate devices (slaves).
  3. Due to the negative historical connotations associated with the terms “master” and “slave,” many organizations and industries are shifting towards using more inclusive language, such as “primary/replica,” “leader/follower,” or “controller/worker.”


The technology term “Master/Slave” has been historically significant in the world of computing and electronics, as it referred to a type of hierarchical communication and control architecture.

In this model, the master device would control and coordinate the activities of one or more subordinate or slave devices, forming an efficient and organized system for data management, communication, and synchronization.

This design allowed for the seamless execution of various tasks that required coordinated operation between different devices and modules.

However, due to the negative connotations associated with the term, and the desire for more inclusive language, the industry has been moving away from the use of “Master/Slave” and adopting alternative terminology, such as “Primary/Secondary” or “Controller/Responder.”


Master/Slave is a communication model often employed in technology systems to streamline processes and manage components effectively. The primary purpose of this model is to delegate control and management duties to a single central entity, called the “Master,” which interacts with and controls multiple subordinated entities, referred to as “Slaves.” This system enables efficient distribution of tasks and resources, ensuring that each component in the system operates according to its specific function.

By regulating each “Slave” device through a centralized command, unintended duplicity of tasks can be avoided, and the system works in harmony, reducing potential issues or errors that may arise if the devices worked independently. A key advantage of the Master/Slave structure is the ease with which large or complex systems can be controlled and monitored.

Examples of this model can be found in various digital and electronic devices, computer hardware systems, and network protocols such as I2C or SPI. A common application is in a database system where the master server manages multiple “Slave” servers, synchronizing, and replicating data across them in real-time to facilitate faster access and provide data redundancy.

In this method, the master server keeps track of changes in the data, maintains stability, and reduces the risk of data loss. By effectively utilizing this hierarchy and distinct roles for each component, the Master/Slave configuration optimizes overall system performance while simultaneously allowing for flexibility and scalability.

Examples of Master/Slave

The technology term “Master/Slave” describes a communication model in which one device (master) controls and directs other devices (slaves). Although this terminology is outdated and considered inappropriate, it was once commonly used in technology systems. Here are three real-world examples of systems that used this concept:

Hard Drives: In older computer systems, two hard drives would be connected using a single Integrated Drive Electronics (IDE) cable. One of the hard drives would be designated as the master, while the other would be the slave. The master drive would be the primary drive for the computer, and the slave drive would be a secondary storage unit.

Databases: In database management systems, master/slave replication refers to a method of copying data from one main database server (master) to one or more secondary servers (slaves) to improve data access and availability. The master server would perform all write operations, while the slave servers would provide read-only copies of the data for clients.

Engineering and computing devices: In robotics and other computerized systems, a master device often commands and oversees the functions of several dependent devices, known as slave units. This configuration simplifies the control architecture and ensures well-coordinated actions among the devices.It is essential to note that the tech industry is moving away from using the terms “master” and “slave” due to their negative connotations. Alternative terms such as “primary/secondary”, “leader/follower”, or “main/replica” are more commonly used today.

Master/Slave Technology FAQ

What is Master/Slave technology?

Master/Slave technology is a communication model and an architectural pattern used primarily in computing and electronics systems. In this model, one device or process (the master) has control over one or more devices or processes (the slaves) and coordinates their activities. The slaves perform tasks requested by the master and report the results back.

What are some common use cases for Master/Slave technology?

Master/Slave technology is commonly used in various applications such as computer hard drives, networked printers, distributed computing systems, databases, robotics, and industrial automation systems. It is also used to synchronize multiple devices, manage high availability configurations, and ensure fault tolerance and redundancy.

Why use Master/Slave architecture over other methodologies?

Master/Slave architecture offers a number of benefits over other methodologies. It simplifies system design by enabling centralized control and management of resources. It can also improve system performance by distributing workloads evenly among slave devices, reducing the overall computational burden on the master device. Additionally, it can improve system reliability by providing built-in redundancy and failover mechanisms, minimizing system downtime.

What are common issues or pitfalls with Master/Slave architecture?

Some common issues and potential pitfalls associated with Master/Slave architecture include single-point-of-failure, scalability, and latency. Since the master device is responsible for managing and coordinating the entire system, it may become a bottleneck or single-point-of-failure if it becomes overloaded or suffers a hardware failure. Scalability can also be an issue, as adding more slaves to the system may place additional burdens on the master device. Lastly, latency can be higher for tasks relying on real-time communication between the master and slaves, especially in large systems or when devices are far apart.

How can I implement fault tolerance and redundancy in a Master/Slave system?

To implement fault tolerance and redundancy in a Master/Slave system, you can employ techniques such as using multiple master devices, implementing backup master devices, or using a voting system to determine a new master when a failure occurs. Dedicated communication links or redundant network paths can also be established between the master and slaves to ensure uninterrupted communication in the event of network failures.

Related Technology Terms

  • Replication
  • Distributed Computing
  • Primary/Secondary
  • Failover
  • Load Balancing

Sources for More Information

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