ceph/doc/rbd/index.rst

   1 ===================
   2  Ceph Block Device
   3 ===================
   4
   5 .. index:: Ceph Block Device; introduction
   6
   7 A block is a sequence of bytes (for example, a 512-byte block of data).
   8 Block-based storage interfaces are the most common way to store data with
   9 rotating media such as hard disks, CDs, floppy disks, and even traditional
  10 9-track tape. The ubiquity of block device interfaces makes a virtual block
  11 device an ideal candidate to interact with a mass data storage system like Ceph.
  12
  13 Ceph block devices are thin-provisioned, resizable and store data striped over
  14 multiple OSDs in a Ceph cluster.  Ceph block devices leverage
  15 :abbr:`RADOS (Reliable Autonomic Distributed Object Store)` capabilities
  16 such as snapshotting, replication and consistency. Ceph's
  17 :abbr:`RADOS (Reliable Autonomic Distributed Object Store)` Block Devices (RBD)
  18 interact with OSDs using kernel modules or the ``librbd`` library.
  19
  20 .. ditaa::  +------------------------+ +------------------------+
  21             |     Kernel Module      | |        librbd          |
  22             +------------------------+-+------------------------+
  23             |                   RADOS Protocol                  |
  24             +------------------------+-+------------------------+
  25             |          OSDs          | |        Monitors        |
  26             +------------------------+ +------------------------+
  27
  28 .. note:: Kernel modules can use Linux page caching. For ``librbd``-based
  29    applications, Ceph supports `RBD Caching`_.
  30
  31 Ceph's block devices deliver high performance with infinite scalability to
  32 `kernel modules`_, or to :abbr:`KVMs (kernel virtual machines)` such as `QEMU`_, and
  33 cloud-based computing systems like `OpenStack`_ and `CloudStack`_ that rely on
  34 libvirt and QEMU to integrate with Ceph block devices. You can use the same cluster
  35 to operate the :ref:`Ceph RADOS Gateway <object-gateway>`, the
  36 :ref:`Ceph File System <ceph-file-system>`, and Ceph block devices simultaneously.
  37
  38 .. important:: To use Ceph Block Devices, you must have access to a running
  39    Ceph cluster.
  40
  41 .. toctree::
  42         :maxdepth: 1
  43
  44         Basic Commands <rados-rbd-cmds>
  45
  46 .. toctree::
  47         :maxdepth: 2
  48
  49         Operations <rbd-operations>
  50
  51 .. toctree::
  52         :maxdepth: 2
  53
  54         Integrations <rbd-integrations>
  55
  56 .. toctree::
  57         :maxdepth: 2
  58
  59         Manpages <man/index>
  60
  61 .. toctree::
  62         :maxdepth: 2
  63
  64         APIs <api/index>
  65
  66 .. _RBD Caching: ./rbd-config-ref/
  67 .. _kernel modules: ./rbd-ko/
  68 .. _QEMU: ./qemu-rbd/
  69 .. _OpenStack: ./rbd-openstack
  70 .. _CloudStack: ./rbd-cloudstack