What is the workflow of retrieving data from Ceph?

The work flow is as follows:

1. The client sends a request to the ceph cluster to retrieve data:

Client could be any of the following

• Ceph Block Device
• Ceph Object Gateway
• Any third party ceph client

2. The client retrieves the latest cluster map from the Ceph Monitor
3. The client uses the CRUSH algorithm to map the object to a placement group. The placement group is then assigned to a OSD.
4. Once the placement group and the OSD Daemon are determined, the client can retrieve the data from the appropriate OSD