The OpenStack Block Storage service works through the interaction of
a series of daemon processes named
cinder-* that reside
persistently on the host machine or machines. You can run all the
binaries from a single node, or spread across multiple nodes. You can
also run them on the same node as other OpenStack services.
To administer the OpenStack Block Storage service, it is helpful to understand a number of concepts. You must make certain choices when you configure the Block Storage service in OpenStack. The bulk of the options come down to two choices - single node or multi-node install. You can read a longer discussion about Storage Decisions in the OpenStack Operations Guide.
OpenStack Block Storage enables you to add extra block-level storage to your OpenStack Compute instances. This service is similar to the Amazon EC2 Elastic Block Storage (EBS) offering.