Providing a fully Object Oriented abstraction, instead of a classic method invocation passing the resources to work on, cinderlib makes it easy to hit the ground running when managing storage resources.
Once Cinder drivers and cinderlib are installed we just have to import the library to start using it:
Usage documentation is not too long and it is recommended to read it all before using the library to be sure we have at least a high level view of the different aspects related to managing our storage with cinderlib.
Before going into too much detail there are some aspects we need to clarify to make sure our terminology is in sync and we understand where each piece fits.
In cinderlib we have Backends, that refer to a storage array’s specific connection configuration so it usually doesn’t refer to the whole storage. With a backend we’ll usually have access to the configured pool.
Resources managed by cinderlib are Volumes and Snapshots, and a Volume can be created from a Backend, another Volume, or from a Snapshot, and a Snapshot can only be created from a Volume.
Once we have a volume we can create Connections so it can be accessible from other hosts or we can do a local Attachment of the volume which will retrieve required local connection information of this host, create a Connection on the storage to this host, and then do the local Attachment.
Given that Cinder drivers are not stateless, cinderlib cannot be either. That’s why we have a metadata persistence plugin mechanism to provide different ways to store resource states. Currently we have memory and database plugins. Users can store the data wherever they want using the JSON serialization mechanism or with a custom metadata plugin.
For extended information on these topics please refer to their specific sections.