---
title: "Block storage\n    | Ubuntu"
description: Ubuntu is an open source software operating system that runs from the
  desktop, to the cloud, to all your internet connected things.
url: https://ubuntu.com/ceph/docs/block-storage?format=md
keywords: index, follow
---

*Submit*

# Block storage

Ceph block storage interacts directly with RADOS and a separate daemon is therefore not required (unlike CephFS and RGW). A Ceph block device is known as a RADOS Block Device (or simply an RBD device) and is available from a newly deployed Ceph cluster. This also makes RBD highly available by default.

### [RBD client usage](https://ubuntu.com/ceph/docs/block-storage?format=md#rbd-client-usage)

This section will provide optional instructions for verifying the RBD service by setting up a simple client environment. Deploy the client using the steps provided in the [Client setup](https://ubuntu.com/ceph/docs/client-setup) appendix.

An example deployment will have a `juju status` output similar to the following:

```
Model  Controller     Cloud/Region     Version  SLA          Timestamp
ceph   my-controller  my-maas/default  3.5.2    unsupported  20:34:16Z

App           Version  Status  Scale  Charm         Channel       Rev  OS      Notes
ceph-mon      18.2.0   active      3  ceph-mon      reef/stable    93  ubuntu
ceph-osd      18.2.0   active      3  ceph-osd      reef/stable   528  ubuntu
ceph-client   22.04    active      1  ubuntu        stable         18  ubuntu

Unit             Workload  Agent  Machine  Public address  Ports   Message
ceph-client/0*   active    idle   3        10.0.0.240              ready
ceph-mon/0       active    idle   0/lxd/1  10.0.0.247              Unit is ready and clustered
ceph-mon/1       active    idle   1/lxd/1  10.0.0.242              Unit is ready and clustered
ceph-mon/2*      active    idle   2/lxd/1  10.0.0.249              Unit is ready and clustered
ceph-osd/0       active    idle   0        10.0.0.229              Unit is ready (2 OSD)
ceph-osd/1*      active    idle   1        10.0.0.230              Unit is ready (2 OSD)
ceph-osd/2       active    idle   2        10.0.0.252              Unit is ready (2 OSD)
```

The client host is represented by the `ceph-client/0` unit.

Create a Ceph pool (‘libvirt-pool’), an RBD user (‘client.libvirt’), collect the user’s keyring file, and transfer it to the client:

```
juju run --wait ceph-mon/0 create-pool name=libvirt-pool app-name=rbd

juju exec --unit ceph-mon/0 -- \
   sudo ceph auth get-or-create client.libvirt \
   mon 'profile rbd' osd 'profile rbd pool=libvirt-pool' | \
   tee ceph.client.libvirt.keyring

juju scp ceph.client.libvirt.keyring ceph-client/0:
```

Connect to the client:

```
juju ssh ceph-client/0
```

**From the RBD client,**

Configure the client using the keyring file and set up the correct permissions:

```
sudo mv ~ubuntu/ceph.client.libvirt.keyring /etc/ceph
sudo chmod 600 /etc/ceph/ceph.client.libvirt.keyring
sudo chown ubuntu: /etc/ceph/ceph.client.libvirt.keyring
```

Install the requisite image creation software and verify that an RBD image can be created:

```
sudo apt install -y qemu-utils
qemu-img create -f raw rbd:libvirt-pool/image-4d:id=libvirt 4G
```

**From the Juju client,**

RBD images/pools can be inspected by querying the cluster with various commands:

```
juju ssh ceph-mon/0 sudo rbd -p libvirt-pool ls
juju ssh ceph-mon/0 sudo rados df --pool libvirt-pool
```

---

[Previous

Object storage](https://ubuntu.com/ceph/docs/object-storage)
[Next

File storage](https://ubuntu.com/ceph/docs/file-storage)

This page was last modified 2 years ago. [Help improve this document in the forum](https://discourse.ubuntu.com/t/block-storage/18821).