@Override
    public String toString() {
        return "LogDirDescription(" +
                "replicaInfos=" + replicaInfos +
                ", error=" + error +
                ", totalBytes=" + totalBytes +
                ", usableBytes=" + usableBytes +
                ')';
    }
The usable size on the volume this log directory is on or empty if the broker did not return a value.
For usable sizes larger than Long.MAX_VALUE, Long.MAX_VALUE is returned.
clients/src/main/java/org/apache/kafka/clients/admin/LogDirDescription.java