架构如下所示，为cinder的官方架构说明：
各个组件介绍如下：
- DB: sql database for data storage. Used by all components.
- 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 ...
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