Reword krbd option description

[pve-docs.git] / pve-storage-rbd.adoc

[[ceph_rados_block_devices]]
Ceph RADOS Block Devices (RBD)
------------------------------
ifdef::wiki[]
:pve-toplevel:
:title: Storage: RBD
endif::wiki[]

Storage pool type: `rbd`

http://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.

krbd::

Access rbd through the krbd kernel module. Optional.

NOTE: Irrespective of the krbd option, containers use always krbd. You can
choose the access method used for VMs, by setting the krbd option.

.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
~~~~~~~~~~~~~~

If you use `cephx` authentication, you need to copy the keyfile from your
external Ceph cluster to a Proxmox VE host.

Create the directory `/etc/pve/priv/ceph` with

 mkdir /etc/pve/priv/ceph

Then copy the keyring

 scp <cephserver>:/etc/ceph/ceph.client.admin.keyring /etc/pve/priv/ceph/<STORAGE_ID>.keyring

The keyring must be named to match your `<STORAGE_ID>`. Copying the
keyring generally requires root privileges.

If Ceph is installed locally on the PVE cluster, this is done automatically by
'pveceph' or in the GUI.

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[]