public boolean cleanSnapshot() {
    return clearSnapshotOfDataRegion(this.dataRegion);
  }
SnapshotTaker takes data snapshot for a DataRegion in one time. It does so by creating hard link
for files or copying them. SnapshotTaker supports two different ways of snapshot: Full Snapshot
and Incremental Snapshot. The former takes a snapshot for all files in an empty directory, and
the latter takes a snapshot based on the snapshot that took before.
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/storageengine/dataregion/snapshot/SnapshotTaker.java