Cinder System Architecture

The Cinder Block Storage Service is intended to be ran on one or more nodes.

Cinder uses a sql-based central database that is shared by all Cinder services in the system. The amount and depth of the data fits into a sql database quite well. For small deployments this seems like an optimal solution. For larger deployments, and especially if security is a concern, cinder will be moving towards multiple data stores with some kind of aggregation system.

Components

Below you will find a brief explanation of the different components.

                                                 /- ( LDAP )
                             [ Auth Manager ] ---
                                    |            \- ( DB )
                                    |
                                    |
                   cinderclient     |
                  /             \   |                   /- [ scheduler ] -- [ volume ] -- ( iSCSI )
[ Web Dashboard ]-               -[ api ] -- < AMQP > --
                  \             /   |                   \- [ backup ]
                   novaclient       |
                                    |
                                    |
                                    |
                                 < REST >

• DB: sql database for data storage. Used by all components (LINKS NOT SHOWN).
• Web Dashboard: potential external component that talks to the api.
• api: component that receives http requests, converts commands and communicates with other components via the queue or http.
• Auth Manager: component responsible for users/projects/and roles. Can backend to DB or LDAP. This is not a separate binary, but rather a python class that is used by most components in the system.
• scheduler: decides which host gets each volume.
• volume: manages dynamically attachable block devices.
• backup: manages backups of block storage devices.