return nil, errUnformattedDisk
			}
			if osIsNotExist(err) {
				return nil, errDiskNotFound
			} else if osIsPermission(err) {
				return nil, errDiskAccessDenied
			}
			storageLogOnceIf(GlobalContext, err, "check-format-json") // log unexpected errors
			return nil, errCorruptedBackend
		} else if osIsPermission(err) {
			return nil, errDiskAccessDenied
		}