Ceph components
Before we dive in, let's take a look at some key components that make up a Ceph cluster. These components are what makes Ceph, and it is important to have a proper understanding of what they are.
A physical node as cluster member
A physical node is the actual server hardware that holds one or more Ceph components.
Maps
In Ceph, maps hold information, such as a list of participating nodes in a cluster and their locations, and data paths, and a list of OSDs with certain data chunks. There are several maps in a Ceph cluster, such as a cluster map, an object storage daemon (OSD) map for a list of OSDs, a monitor map for known monitor nodes, a placement group (PG) map for the location of objects or data chunks, and a CRUSH map to determine how to store and retrieve data by computing the data storage location.
A cluster map
A cluster map is a map of devices and buckets that compose a Ceph cluster. Ceph uses a bucket hierarchy to define nodes or node locations, such as a room, rack,...