OBJECT STORAGE DEVICE (OSD): In CEPH, an OSD is a software component residing on each storage node, responsible for storing data as objects, replicating them, and ensuring their availability.
Analogy: Imagine each OSD as a librarian responsible for a specific section of the library, managing the books (data objects) within their assigned area.
Why It Matters: OSDs are the building blocks of CEPH storage, providing data locality, redundancy, and parallel access.