@Override
  protected boolean downgradeToSharedTableLock() {
    // return true here to change from exclusive lock to shared lock, so we can still assign regions
    // while taking snapshots. This is important, as region server crash can happen at any time, if
    // we can not assign regions then the cluster will be in trouble as the regions can not online.
    return true;
  }
Takes a snapshot of the mob region
hbase-server/src/main/java/org/apache/hadoop/hbase/master/snapshot/EnabledTableSnapshotHandler.java