SNN will always upload fsimage

boolean sendRequest = isPrimaryCheckPointer
    || secsSinceLastUpload >= checkpointConf.getQuietPeriod();
doCheckpoint(sendRequest);

if (ie == null && ioe == null) {
  //Update only when response from remote about success or
  lastUploadTime = monotonicNow();
  // we are primary if we successfully updated the ANN
  this.isPrimaryCheckPointer = success;
}