What is a Mainframe?

A mainframe is a large computer capable of processing large numbers of transactions in a minimal amount of time. Mainframe computers are created to enable reliable, secure, and fast data transfer between different software components, servers, and services. Banks and other large organizations use mainframe computing for large-scale data processing, transactions, and enterprise apps, exceeding the demands of a conventional server. While mainframe computers still have a place in specific industries and applications, many organizations are modernizing mainframe applications to leverage the capabilities of the cloud.

The term mainframe originated in the 1950s, when these high-performance computers required large physical enclosures. Modern mainframe cabinets are roughly the size of a refrigerator. This system supports multiple users and terminals in real time.

Over the decades, commercial servers and personal computers have taken over roles once handled by the early computer mainframes. Much of this mainframe infrastructure is now migrating to cloud computing services. However, mainframes remain important to governments, financial institutions, aviation services, healthcare, and other critical industries.

Modern mainframe computers are more powerful than their predecessors because of rapid advancements in the underlying infrastructure. A single mainframe computer may handle billions of transactions daily and support batch processing. Mainframe computers allow you to share data, access resources, regulate access, and distribute resources to users.

Mainframe computers handle massive data and transaction workloads with high-throughput data processing and coordination with external application services. Administrators can configure, govern, and manage compute capabilities through the mainframe's centralized management consoles. Dedicated hardware modules, including the CPU, specialized processors, and I/O, ensure high-throughput data processing for transactional workloads and other specialized computing needs.

The following are key components of modern mainframe computers.

Central processing units (CPUs)

Early mainframes ran with a single central processing unit (CPU). However, modern mainframes use multiple processor cores for faster processing and more computing power.

System assistance processor (SAP)

The SAP is responsible for passing the data from one device to another, allowing the CPU to focus on data processing.

Control unit

Mainframe computers depend on the control unit to manage communications between processors, I/O channels, and other connected devices.

Input/output (I/O) cards

A mainframe transfers data to connected devices through multiple I/O cards. If one I/O card fails, another replaces it to prevent operational disruption.

Storage space

Mainframe systems store and process very large amounts of data in hard drives or other storage systems, enabling quick retrieval and strict access control.

Clustering technologies

Multiple mainframe systems can combine to increase processing power. With this setup, the system can distribute data to individual mainframes to accelerate processing.

Multiple operating systems

A mainframe computer can support multiple operating systems through virtualization technologies. Virtual machines allow efficient resource allocation to workloads and applications running within each virtualized environment.

Database management system

Mainframe computers include a database management system, which enables them to store, manage, and share data with multiple end devices.

Mainframe technology excels at applications that require reliable, low-latency, and concurrent data processing. The following are some common applications of mainframe computing.

Financial transaction processing

Banks, investment firms, insurance companies, and other financial institutions store, process, and retrieve transactional data in mainframe computers. For example, when you make a withdrawal from an automated teller machine (ATM), the mainframe computer checks its internal database before approving the transaction.

Large-scale data processing and statistical analysis

Mainframe computing enables you to run machine learning models, predictive analytics, and other statistical workloads to derive insights from structured data. For example, a university department has a massive space dataset that it uses to run queries to discover more about the known universe.

Enterprise resource planning

Some enterprise resource planning (ERP) software still relies on mainframe systems for data processing power and management. Mainframe computing ensures consistent access to data and allows you to integrate your ERP system with other enterprise applications. Additionally, some industries must adhere to laws to store sensitive data on-premises in mainframe storage.

AI inferencing workloads

Modern mainframe architecture can support large-scale deployment and inference of large language models for various AI applications in transactional processing. For example, a bank can deploy an AI application on a mainframe computer to monitor for transactional fraud. The application can analyze transactions in real time, which it can use to triage potential fraud.

Supercomputers are high-performance computers capable of performing complex floating-point operations (FLOP) at a large scale. They often have more FLOP throughput than a mainframe. On the other hand, a mainframe supports millions of small data operations in real time. Supercomputers excel at compute-intensive workloads like high-performance computing, machine learning (ML) training, and big data analytics. Meanwhile, the mainframe allows businesses to handle transactional processing, manage inventories, and run data replication with exceptional reliability.

A server is a discrete computer system that provides a range of services and resources to users. Servers can be used for a range of different tasks. Servers can be clustered to operate in tandem, where large-scale applications are orchestrated across systems.

Meanwhile, a mainframe system is a larger and more powerful computer system than a single server, providing quick access to stored information and high-speed processing. Mainframe computers typically run high-performance, specialized applications. Mainframe computers are specifically designed to provide greater reliability and availability than commercial servers. Mainframe computers have reliability built into their specialized hardware architecture, whereas server architectures rely on software-routed failover mechanisms for reliability.