Chapter 2. Requirements for scaling storage

Always ensure that you have plenty of storage capacity.

If storage ever fills completely, it is not possible to add capacity or delete or migrate content away from the storage to free up space completely. Full storage is very difficult to recover.

Capacity alerts are issued when cluster storage capacity reaches 75% (near-full) and 85% (full) of total capacity. Always address capacity warnings promptly, and review your storage regularly to ensure that you do not run out of storage space.

If storage capacity reaches 85% full state, Ceph may report HEALTH_ERR and prevent IO operations. In this case, you can increase the full ratio temporarily so that cluster rebalance can take place. For steps to increase the full ratio, see Setting Ceph OSD full thresholds using the ODF CLI tool.

If you do run out of storage space completely, contact Red Hat Customer Support.