protected void setFlushSizeLowerBounds(HRegion region) {
    int familyNumber = region.getTableDescriptor().getColumnFamilyCount();
    // For multiple families, lower bound is the "average flush size" by default
    // unless setting in configuration is larger.
    flushSizeLowerBound = region.getMemStoreFlushSize() / familyNumber;
    long minimumLowerBound = getConf().getLong(HREGION_COLUMNFAMILY_FLUSH_SIZE_LOWER_BOUND_MIN,
      DEFAULT_HREGION_COLUMNFAMILY_FLUSH_SIZE_LOWER_BOUND_MIN);
    if (minimumLowerBound > flushSizeLowerBound) {
      flushSizeLowerBound = minimumLowerBound;
    }
    // use the setting in table description if any
    String flushedSizeLowerBoundString =
      region.getTableDescriptor().getValue(HREGION_COLUMNFAMILY_FLUSH_SIZE_LOWER_BOUND);
    if (flushedSizeLowerBoundString == null) {
      LOG.debug(
        "No {} set in table {} descriptor;"
          + "using region.getMemStoreFlushHeapSize/# of families ({}) " + "instead.",
        HREGION_COLUMNFAMILY_FLUSH_SIZE_LOWER_BOUND, region.getTableDescriptor().getTableName(),
        StringUtils.humanSize(flushSizeLowerBound) + ")");
    } else {
      try {
        flushSizeLowerBound = Long.parseLong(flushedSizeLowerBoundString);
      } catch (NumberFormatException nfe) {
        // fall back for fault setting
        LOG.warn(
          "Number format exception parsing {} for table {}: {}, {}; "
            + "using region.getMemStoreFlushHeapSize/# of families ({}) "
            + "and region.getMemStoreFlushOffHeapSize/# of families ({}) " + "instead.",
          HREGION_COLUMNFAMILY_FLUSH_SIZE_LOWER_BOUND, region.getTableDescriptor().getTableName(),
          flushedSizeLowerBoundString, nfe, flushSizeLowerBound);

      }
    }
  }
A {@link FlushPolicy} that only flushes store larger a given threshold. If no store is large
enough, then all stores will be flushed.
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/FlushLargeStoresPolicy.java