Notice
This document is for a development version of Ceph.
Ceph Block Device
A block is a sequence of bytes (often 512).Block-based storage interfaces are a mature and common way to store data onmedia including HDDs, SSDs, CDs, floppy disks, and even tape.The ubiquity of block device interfaces is a perfect fit for interactingwith mass data storage including Ceph.
Ceph block devices are thin-provisioned, resizable, and store data striped overmultiple OSDs. Ceph block devices leverageRADOS capabilitiesincluding snapshotting, replication and strong consistency. Ceph blockstorage clients communicate with Ceph clusters through kernel modules orthelibrbd library.
Note
Kernel modules can use Linux page caching. Forlibrbd-basedapplications, Ceph supportsRBD Caching.
Ceph’s block devices deliver high performance with vast scalability tokernel modules, or toKVMs such asQEMU, andcloud-based computing systems likeOpenStack,OpenNebula andCloudStackthat rely on libvirt and QEMU to integrate with Ceph block devices. You can usethe same cluster to operate theCeph RADOS Gateway, theCeph File System, and Ceph block devices simultaneously.
Important
To use Ceph Block Devices, you must have access to a runningCeph cluster.
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