The Block Storage service enables management of volumes, volume snapshots, and volume types. It includes the following components:
cinder-api: Accepts API requests and routes them tocinder-volumefor action.cinder-volume: Responds to requests to read from and write to the Block Storage database to maintain state, interacting with other processes (likecinder-scheduler) through a message queue and directly upon block storage providing hardware or software. It can interact with a variety of storage providers through a driver architecture.cinder-schedulerdaemon: Like thenova-scheduler, picks the optimal block storage provider node on which to create the volume.Messaging queue: Routes information between the Block Storage service processes.
The Block Storage service interacts with Compute to provide volumes for instances.

