Table of Contents

• Commands
  • Modify Pool Replica Count
  • Show current space used
  • Show status
  • List, create and delete volumes
  • Presenting a volume to this host
  • Snapshots
  • Save RBD as file

Commands

Modify Pool Replica Count

Show and modify the replica count (size) in a given pool.

You can do the same with min_size if needed.

# Show the current replica count
#   ceph osd pool get <pool name> size
ceph osd pool get images size

# Set the replica count for a given pool
#   ceph osd pool set <pool name> size <number of replicas>
ceph osd pool set images size 2

Show current space used

ceph df

Show status

# Show the status right now
ceph -s

# Show the status and watch it
ceph -w

List, create and delete volumes

# LIST
# rbd ls -p <pool name>
rbd ls -p volumes

# CREATE
#   rbd create --size <size in gb> <pool>/<volume id>
rbd create --size 10 volumes/myVolume

# DELETE
#   rbd rm <pool>/<volume id>
rbd rm volumes/myVolume

Presenting a volume to this host

# PRESENT TO HOST
#   rbd map <pool>/<volume id>
rbd map volumes/myVolume

# LIST MAPPED
rbd showmapped

# REMOVE FROM HOST
#   rbd unmap <pool>/<volume id>
rbd unmap volumes/myVolume

Once you've presented the volume you can use it like this:

mkfs.ext4 /dev/rbd0
mkdir /data
mount /dev/rbd0 /data

Snapshots

# LIST SNAPSHOTS
#   rbd snap ls <pool>/<volume id>
rbd snap ls volumes/myVolume

# REVERT TO SNAPSHOT
# rbd snap rollback <pool>/<volume id>@<snapshot id>
rbd snap rollback volumes/myVolume@sampleSnapshot

# DELETE SNAPSHOT
#   rbd snap rm <pool>/<volume id>@<snap id>
rbd snap rm volumes/myVolume@sampleSnapshot

Save RBD as file

#   rbd export <pool>/<volume> <filename>
rbd export volumes/myVolume myVolume.raw