A server is simply a computer or program that gives services to another program and its user, known as the client. In data centers, the actual physical machine running the server program is often called a server too. This machine could be a dedicated server, or it could handle other tasks as well.
In a client/server setup, the server listens for requests from the client, which might be on the same machine or a different one. An application can act both as a client, requesting services, and as a server, providing services to other applications.
How Servers Work
The term “server” can refer to hardware, virtual machines, or the software providing server services. Depending on how it’s used, a server operates differently.
Physical and Virtual Servers
A physical server is essentially a computer running server software. It usually has more robust features compared to regular desktop computers, which we’ll get into later.
Virtual servers are like digital replicas of physical servers. Each virtual server has its own operating system and applications, isolated from others on the same physical machine. To create these virtual machines, an administrator installs a lightweight software called a hypervisor on the physical server, allowing it to share its hardware resources—like CPU, memory, and storage—among various virtual machines. This setup cuts hardware costs since one physical server can run multiple virtual servers.
Server Software
Every server needs at least two key software components: an operating system and an application. The operating system is like the foundation for the server application, ensuring it can access hardware resources and communicate with clients effectively. The IP address and domain name are assigned at this level too.
Desktop Computers vs. Servers
Servers and desktop computers share some similarities, as both typically use X86/X64 CPUs and can run similar software. However, servers often have multiple CPU sockets and error-correcting memory. They usually support extensive memory capacities compared to desktops.
Since servers handle critical workloads, manufacturers design them with redundancy in components. For instance, many servers come with backup power supplies and network interfaces, ensuring they keep running even if a part fails.
In terms of size, modern desktops usually come in compact forms, while most servers are rack-mounted. This means they fit into standardized metal frames, categorized by how much space they occupy—like 1U, 2U, or 4U, which refers to their height in rack units.
You can’t swap desktop operating systems, like Windows 10, for server operating systems. While Windows 10 has some server-like features, it’s not built for extensive server tasks. For example, Windows Server’s version of Hyper-V is made for managing virtual servers while Windows 10’s is more for development.
Types of Servers
Servers can be categorized by what they do. Here are a few examples:
- Web Server: Serves up HTML pages or files to clients, like web browsers.
- Application Server: Provides business logic for applications in a distributed network.
- Proxy Server: Acts as a middleman between a client device and another server.
- Mail Server: Handles incoming and outgoing emails.
- Virtual Server: Operates on shared hardware but gives users an isolated experience.
- Blade Server: Contains multiple thin circuit boards, each functioning as an independent server.
- File Server: Centralizes data storage so network computers can access files.
- Policy Server: Controls authorization and file tracking in a network.
- Database Server: Hosts databases and processes queries from client applications.
- Print Server: Manages print requests from networked devices.
Server Components
Physically, servers consist of different components. They usually have a rack mount chassis with a power supply, system board, multiple CPUs, memory, storage, and a network interface. Most serve as out-of-band management tools, which means they allow administrators to manage the server without relying on the operating system. They can remotely power the server on or off and perform health checks.
The server operating system, such as Windows Server or Linux, is essential for running applications and ensuring hardware access and network connectivity. Each application is key to the server’s role, whether that be for managing databases or emails.
Choosing the Right Server
When selecting a server, consider factors like virtual machine consolidation and security features to protect data. Think about the internal storage—disk capacity and types can affect performance significantly.
As organizations lean on virtualization, they often run multiple workloads on fewer physical servers, cutting costs and saving space. However, this can increase risk; if one server fails, it impacts more workloads.
Regular maintenance is vital. Administrators need to check both hardware and software proactively to keep the server running smoothly. A maintenance checklist should cover all these bases to ensure everything remains in good health.