Understanding Cloud Block Storage

Cloud Block Storage provides persistent block-level storage volumes for use with Rackspace cloud servers. Cloud Block Storage enables customers to scale their storage independently of their compute resources.

Cloud Block Storage is based on the OpenStack Block Storage service (project named cinder) and leverages open-source software and commodity hardware components to provide a low-cost alternative to traditional third-party SAN (storage area network) vendors. The underlying hardware consists of individual storage nodes that provide either standard or SSD disks in a protected RAID10 configuration. The distributed storage node system of Cloud Block Storage makes it horizontally scalable and free from monolithic failure scenarios.

Cloud Block Storage volumes can be provisioned in 1 GB increments, ranging from 100 GB to 1 TB in size. You can attach up to 10 Cloud Block Storage volumes per cloud server. Volumes are exposed to the hypervisor via iSCSI over a logical network and are presented to servers as virtual devices (local disks). After a volume is attached to a server, you must prepare the volume for use by partitioning, formatting, and mounting it through the server operating system.

Most servers can boot from a network-attached Cloud Block Storage volume. You can create a bootable Cloud Block Storage volume and launch a server instance from that volume. Booting from a volume enables diskless servers, new server configurations such as high RAM/low storage, and staging of common server images in Cloud Block Storage.


For instructions on using the Cloud Block Storage boot-from-volume feature, see Boot a server from a Cloud Block Storage volume.

The Rackspace technical documentation provides many more details about Cloud Block Storage. Begin exploring at Cloud Block Storage support.