public String toString() {
    return "dir=" + getDir() + " maxSpace=" + getCapacity()
        + " usedSpace=" + getUsedSpace() + " availableSpace="
        + getAvailableSpace();
  }
For testing purposes we can set the disk directory size in bytes *
geode-core/src/main/java/org/apache/geode/internal/cache/DirectoryHolder.java