The Loki Operator requires two distinct types of storage for two different purposes. Long-term storage requires access to an object based data store, while temporary storage must be file or block based storage.

The installation documentation within the Logging Operator docs does specifically lists supported object stores as a prerequisite, but does not mention the temporary storage requirement. Instead, the temporary storage is mentioned in a footnote on the example LokiStack instance YAML. Even then it only recommends a storage class that allocates block storage for performance and directs the reader to consult the available storage classes for the cluster.

As such, the documentation does not explicitly indicate that object storage can not be used for temporary storage. The instruction to check available storage classes implies that any of the storage classes in the cluster can be used when this is not the case.

The same issue exists in all versions of the OpenShift Container Platform documentation where the Loki Operator is a supported log storage option, up to and including version 4.17