DevOps Dictionary

Xen is an open-source type-1 hypervisor that runs directly on bare-metal hardware to host multiple isolated virtual machines (VMs) on a single server. It solves the problem of safely sharing compute resources across different workloads by virtualizing CPU, memory, storage, and networking so each VM behaves like an independent machine. At a high level, Xen schedules access to hardware, enforces isolation boundaries between guests, and typically uses a privileged management domain (often Dom0) to provide device drivers and handle VM lifecycle operations while guest VMs run their own operating systems.

With Xen, teams can consolidate servers, improve utilization, and apply consistent isolation and operational controls; without it, workloads often require dedicated machines or rely on weaker separation, increasing cost, sprawl, and the blast radius of failures or compromise. This gap exists because the hypervisor layer can mediate hardware access in a way a general-purpose OS cannot reliably enforce between competing tenants.