PLACEMENT GROUP (PG): In CEPH, a PG is a logical grouping of objects within a pool, further dividing data for efficient distribution, replication, and management.
Analogy: Consider each PG as a shelf within a library section, organizing related books (data objects) together for easy access and management.
Why It Matters: PGs enhance data distribution, load balancing, and fault tolerance by mapping objects to specific OSDs and enabling parallel operations.