1.4.4. Block Storage Service
The Block Storage (or volume) service provides persistent block storage management for virtual hard drives. The Block Storage service manages the creation of block devices to servers. Block storage volumes are fully integrated into both the Compute and Dashboard services, which allows cloud users to manage their own storage needs (Compute handles the attaching and detaching of devices). For more information, see Section 1.4.5, “Compute Service”. Both regions and zones (for details, refer to Section 1.4.7, “Object Storage Service”) can be used to handle distributed block storage hosts.
Block storage is appropriate for performance-sensitive scenarios such as database storage, expandable file systems, or providing a server with access to raw block-level storage. Additionally, snapshots can be taken to either restore data or to create new block storage volumes (snapshots are dependent upon driver support).
Basic operations include:
- Create, list, and delete volumes.
- Create, list, and delete snapshots.
- Attach and detach volumes to running virtual machines.
Table 1.5. Block Storage Service components
| Component | Description |
|---|---|
|
openstack-cinder-volume
|
Carves out storage for virtual machines on demand. A number of drivers are included for interaction with storage providers.
|
|
openstack-cinder-api
|
Responds to and handles requests, and places them in the message queue.
|
|
openstack-cinder-backup
|
Provides the ability to back up a Block Storage volume to an object store.
|
|
openstack-cinder-scheduler
|
Assigns tasks to the queue and determines the provisioning volume server.
|
|
Database
|
Provides state information.
|