public static HRegion openHRegion(final Path rootDir, final RegionInfo info,
    final TableDescriptor htd, final WAL wal, final Configuration conf,
    final RegionServerServices rsServices, final CancelableProgressable reporter)
    throws IOException {
    FileSystem fs = null;
    if (rsServices != null) {
      fs = rsServices.getFileSystem();
    }
    if (fs == null) {
      fs = rootDir.getFileSystem(conf);
    }
    return openHRegion(conf, fs, rootDir, info, htd, wal, rsServices, reporter);
  }
Open a Region.
@param rootDir    Root directory for HBase instance
@param info       Info for region to be opened.
@param htd        the table descriptor
@param wal        WAL for region to use. This method will call WAL#setSequenceNumber(long)
                  passing the result of the call to HRegion#getMinSequenceId() to ensure the
                  wal id is properly kept up. HRegionStore does this every time it opens a new
                  region.
@param conf       The Configuration object to use.
@param rsServices An interface we can request flushes against.
@param reporter   An interface we can report progress against.
@return new HRegion
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/HRegion.java