:fn-ceph-user-mgmt: footnote:cephusermgmt[Ceph user management {cephdocs-url}/rados/operations/user-management/]
[[ceph_rados_block_devices]]
Ceph RADOS Block Devices (RBD)
------------------------------
ifdef::wiki[]
:pve-toplevel:
:title: Storage: RBD
endif::wiki[]

Storage pool type: `rbd`

https://ceph.com[Ceph] is a distributed object store and file system
designed to provide excellent performance, reliability and
scalability. RADOS block devices implement a feature rich block level
storage, and you get the following advantages:

* thin provisioning
* resizable volumes
* distributed and redundant (striped over multiple OSDs)
* full snapshot and clone capabilities
* self healing
* no single point of failure
* scalable to the exabyte level
* kernel and user space implementation available

NOTE: For smaller deployments, it is also possible to run Ceph
services directly on your {pve} nodes. Recent hardware has plenty
of CPU power and RAM, so running storage services and VMs on same node
is possible.

[[storage_rbd_config]]
Configuration
~~~~~~~~~~~~~

This backend supports the common storage properties `nodes`,
`disable`, `content`, and the following `rbd` specific properties:

monhost::

List of monitor daemon IPs. Optional, only needed if Ceph is not running on the
{pve} cluster.

pool::

Ceph pool name.

username::

RBD user ID. Optional, only needed if Ceph is not running on the {pve} cluster.
Note that only the user ID should be used. The "client." type prefix must be
left out.

krbd::

Enforce access to rados block devices through the krbd kernel module. Optional.

NOTE: Containers will use `krbd` independent of the option value.

.Configuration Example for a external Ceph cluster (`/etc/pve/storage.cfg`)
----
rbd: ceph-external
        monhost 10.1.1.20 10.1.1.21 10.1.1.22
        pool ceph-external
        content images
        username admin
----

TIP: You can use the `rbd` utility to do low-level management tasks.

Authentication
~~~~~~~~~~~~~~

NOTE: If Ceph is installed locally on the {pve} cluster, the following is done
automatically when adding the storage.

If you use `cephx` authentication, which is enabled by default, you need to
provide the keyring from the external Ceph cluster.

To configure the storage via the CLI, you first need to make the file
containing the keyring available. One way is to copy the file from the external
Ceph cluster directly to one of the {pve} nodes. The following example will
copy it to the `/root` directory of the node on which we run it:

----
# scp <external cephserver>:/etc/ceph/ceph.client.admin.keyring /root/rbd.keyring
----

Then use the `pvesm` CLI tool to configure the external RBD storage, use the
`--keyring` parameter, which needs to be a path to the keyring file that you
copied.  For example:

----
# pvesm add rbd <name> --monhost "10.1.1.20 10.1.1.21 10.1.1.22" --content images --keyring /root/rbd.keyring
----

When configuring an external RBD storage via the GUI, you can copy and paste
the keyring into the appropriate field.

The keyring will be stored at

----
# /etc/pve/priv/ceph/<STORAGE_ID>.keyring
----

TIP: Creating a keyring with only the needed capabilities is recommend when
connecting to an external cluster. For further information on Ceph user
management, see the Ceph docs.footnoteref:[cephusermgmt,{cephdocs-url}/rados/operations/user-management/[Ceph User Management]]

Ceph client configuration (optional)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Connecting to an external ceph storage doesn't always allow setting
client-specific options in the config DB on the external cluster. You can add a
`ceph.conf` beside the ceph keyring to change the ceph client configuration for
the storage.

The ceph.conf needs to have the same name as the storage.

----
# /etc/pve/priv/ceph/<STORAGE_ID>.conf
----

See the RBD configuration reference footnote:[RBD configuration reference
{cephdocs-url}/rbd/rbd-config-ref/] for possible settings.

NOTE: Do not change these settings lightly. {PVE} is merging the
<STORAGE_ID>.conf with the storage configuration.


Storage Features
~~~~~~~~~~~~~~~~

The `rbd` backend is a block level storage, and implements full
snapshot and clone functionality.

.Storage features for backend `rbd`
[width="100%",cols="m,m,3*d",options="header"]
|==============================================================================
|Content types  |Image formats  |Shared |Snapshots |Clones
|images rootdir |raw            |yes    |yes       |yes
|==============================================================================

ifdef::wiki[]

See Also
~~~~~~~~

* link:/wiki/Storage[Storage]

endif::wiki[]

