A Placement Group (PG) is a logical collection of objects that are replicated on OSDs to provide reliability in a storage system. Depending on the replication level of a Ceph pool, each PG is replicated and distributed on more than one OSD of a Ceph cluster. You can consider a PG as a logical container holding multiple objects, such that this logical container is mapped to multiple OSDs:
The PGs are essential for the scalability and performance of a Ceph storage system. Without PGs, it will be difficult to manage and track tens of millions of objects that are replicated and spread over hundreds of OSDs. The management ...
