Block Storage Service

Ceph block storage is also called a RADOS block device (RBD). Ceph introduces a new RBD protocol for block devices. RBD provides reliable, distributed, and high-performance block storage for clients. RBD blocks are striped and distributed on multiple Ceph objects. These objects are distributed in the entire Ceph storage cluster, ensuring data reliability and performance. RBD has been supported by the Linux kernel. The RBD driver has been well integrated with the Linux kernel over the past few years. Almost all Linux OS distributions support RBD. In addition to reliability and performance, RBD also supports other enterprise-level features, such as full and incremental snapshot, thin provisioning, copy-on-write clone. RBD also supports full memory caching, which can greatly improve its performance.

A Ceph RBD image can be used as a drive mapped to a physical bare-metal server (BMS), a virtual machine (VM), or another host. Industry-leading open-source hypervisors, such as KVM and Xen, fully support RBD and use RBD to provide block storage services for VMs.

Ceph block devices fully support cloud platforms such as OpenStack. In OpenStack, Ceph block devices can be used through cinder (block) and glance (image) components. In this way, the copy-on-write feature of the Ceph block storage can be used to create thousands of VMs in a short time.