First, we will create a pool to store the images we create later. We could supply placement groups and other information if needed.
sudo ceph osd pool create rbdpool
Next, we will initialize the pool so it will have the application of the rbd set. This command will add the meta required to host images.
sudo rbd pool init rbdpool
We will create our first image called disk1. It will be 4G in size and have the layering feature. There is a bunch of different image features to choose from:
- layering: layering support
- striping: striping v2 support
- exclusive-lock: exclusive locking support
- object-map: object map support (requires exclusive-lock)
- fast-diff: fast diff calculations (requires object-map)
- deep-flatten: snapshot flatten support
- journaling: journaled IO support (requires exclusive-lock)
- data-pool: erasure-coded pool support
The one that is most appropriate here is layering. Next, if not already mentioned in your configuration(/etc/ceph/ceph.conf), we could supply the monitor IP. Next, we could provide the key file if not present in the regular place. And lastly, we will add which pool to create the image.
sudo rbd create disk1 --size 4096 --image-feature layering -m 192.168.6.43 -k /etc/ceph/ceph.client.admin.keyring -p rbdpool
On the client, we can now map the drive. This command will use the same parameters with the addition of the client's name to connect.
sudo rbd map disk1 --name client.admin -m 192.168.6.43 -k /etc/ceph/ceph.client.admin.keyring -p rbdpool
Next, we will create a filesystem on the image available as a device on your system under /dev/rdb, then there will be a directory with the name of your pool and lastly, the name of the image as a link to the rbd device created.
sudo mkfs.ext4 -m0 /dev/rbd/rbdpool/disk1
Lastly, mounting the device is just using the device and mounting to a mount-point exactly as typical mounting.
sudo mount /dev/rbd/rbdpool/disk1 /mnt/ceph-block-device
First, we need to add a configuration for the rbdmap service in the file /etc/ceph/rbdmap. This configuration will map the image disk1 on pool rbdpool. Next, we add the parameter id of the client to connect. Finally, we need to add the keyring with the access key for this pool.
rbdpool/disk1 id=admin,keyring=/etc/ceph/ceph.client.admin.keyring
To get this drive mapped, we start the rbdmap service.
sudo systemctl start rbdmap
Next, we will create a filesystem on the image available as a device on your system under /dev/rdb, then there will be a directory with the name of your pool and lastly, the name of the image as a link to the rbd device created.
sudo mkfs.ext4 -m0 /dev/rbd/rbdpool/disk1
Next, we add a configuration in /etc/fstab. Pretty much what you would expect to mount the disk1 image into our mount-point /mnt/ceph-block-device. The filesystem is ext4, and we need to supply the flag noauto as the system might try to mount the device before it's actually mapped. The rbdmap service will mount the drive when the image is mapped.
/dev/rbd/rbdpool/disk1 /mnt/ceph-block-device ext4 noauto 0 0