The RADOS block device (RBD)—formerly known as the Ceph block device—provides block-based persistent storage to Ceph clients, which they use as an additional disk. The client has the flexibility to use the disk as they require, either as a raw device or by formatting it with a filesystem followed by mounting it. A RADOS block device makes use of the librbd library and stores blocks of data in a sequential form striped over multiple OSDs in a Ceph cluster. RBD is backed by the RADOS layer of Ceph, and thus, every block device is spread over multiple Ceph nodes, delivering high performance and excellent reliability. RBD is rich with enterprise features such as thin provisioning, dynamically resizable, snapshots, copy-on-write, and caching, among others. The RBD protocol is fully supported with Linux as a mainline kernel driver; it also supports various virtualization platforms such as KVM, Qemu, and libvirt, allowing virtual machines to take advantage of a Ceph block...