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Thick-provisioning was introduced to make accounting of assigned space for volumes easier. When thick-provisioned volumes are the only consumer of the Ceph cluster, this works fine. However, it is unlikely that this is the case. Instead, accounting of the requested (thin-provisioned) size of volumes is much more practical as different types of volumes can be tracked. OpenShift already provides cluster-wide quotas, which can combine accounting of requested volumes by grouping different StorageClasses. In addition to the difficult practise of allowing only thick-provisioned RBD backed volumes, the performance makes thick-provisioning troublesome. As volumes need to be completely allocated, data needs to be written to the volume. This can take a long time, depending on the size of the volume. Provisioning, cloning and snapshotting becomes very much noticeable, and because of the additional time consumption, more prone to failures. Signed-off-by: Niels de Vos <ndevos@redhat.com>