public static String getWALArchiveDirectoryName(Configuration conf, final String serverName) {
    StringBuilder dirName = new StringBuilder(HConstants.HREGION_OLDLOGDIR_NAME);
    if (conf.getBoolean(SEPARATE_OLDLOGDIR, DEFAULT_SEPARATE_OLDLOGDIR)) {
      dirName.append(Path.SEPARATOR);
      dirName.append(serverName);
    }
    return dirName.toString();
  }
Construct the directory name for all old WALs on a given server. The default old WALs dir looks
like: <code>hbase/oldWALs</code>. If you config hbase.separate.oldlogdir.by.regionserver to
true, it looks like <code>hbase//oldWALs/kalashnikov.att.net,61634,1486865297088</code>.
@param serverName Server name formatted as described in {@link ServerName}
@return the relative WAL directory name
hbase-server/src/main/java/org/apache/hadoop/hbase/wal/AbstractFSWALProvider.java