What Is a Server?
A server is a computer that provides services, resources, or data to other computers — called clients — over a network. In a data center, servers are the workhorses that run applications, databases, and virtual machines.
What's Inside a Server
CPU & memory
One or more processors and large amounts of ECC RAM.
Storage
SSDs or HDDs, often behind a RAID controller.
Networking
Multiple NICs for redundancy and throughput.
BMC & power
A management controller and redundant power supplies.
Ways Servers Are Built and Used
By role, servers include web, application, database, file, mail, and virtualization or hypervisor hosts. By form factor, they are typically rack servers (measured in U), blade servers in a shared enclosure, or tower servers for smaller sites — plus hyperconverged nodes that combine compute and storage.
A Server Is Only as Reliable as Its Hardware
Across a thousand servers, component failures — fans, power supplies, disks, memory, NICs — add up to hundreds of events a year. Most monitoring only sees a server once its OS is running. Monitoring the hardware underneath, through the management controller, is how those failures get caught before they take an application down.