A storage grade identifies the type of storage used by a Storage Node to store object data, for example, flash or spinning disk. If you use more than one type of storage, you can optionally create a storage grade to identify each type. Creating storage grades makes it easier to select the Storage Node when configuring storage pools.
When creating storage grades, do not create more storage grades than necessary. For example, do not create one storage grade for each Storage Node. Instead, assign each storage grade to two or more nodes. Storage grades assigned to only one node can cause ILM backlogs if that node becomes unavailable.