The default OpenStack Block Storage service implementation is an
iSCSI solution that uses Logical Volume Manager (LVM) for Linux.

This high-level procedure shows you how to create and attach a volume
to a server instance.

To create and attach a volume to an instance

1. Configure the OpenStack Compute and the OpenStack Block Storage
   services through the /etc/cinder/cinder.conf file.
2. Use the openstack volume create command to create a
   volume. This command creates an LV into the volume group (VG)
   cinder-volumes.
3. Use the openstack server add volume command to attach the
   volume to an instance. This command creates a unique IQN <iSCSI
Qualified Name (IQN)> that is exposed to the compute node.
   • The compute node, which runs the instance, now has an active iSCSI
     session and new local storage (usually a /dev/sdX
     disk).
   • Libvirt uses that local storage as storage for the instance. The
     instance gets a new disk (usually a /dev/vdX disk).

For this particular walkthrough, one cloud controller runs
nova-api, nova-scheduler,
nova-conductor and cinder-* services. Two
additional compute nodes run nova-compute. The walkthrough
uses a custom partitioning scheme that carves out 60 GB of space and
labels it as LVM. The network uses the FlatManager and
NetworkManager settings for OpenStack Compute.

The network mode does not interfere with OpenStack Block Storage
operations, but you must set up networking for Block Storage to work.
For details, see networking.

To set up Compute to use volumes, ensure that Block Storage is
installed along with lvm2. This guide describes how to
troubleshoot your installation and back up your Compute volumes.