public static String getWALDirectoryName(final String serverName) {
    StringBuilder dirName = new StringBuilder(HConstants.HREGION_LOGDIR_NAME);
    dirName.append("/");
    dirName.append(serverName);
    return dirName.toString();
  }
Construct the directory name for all WALs on a given server. Dir names currently look like this
for WALs: <code>hbase//WALs/kalashnikov.att.net,61634,1486865297088</code>.
@param serverName Server name formatted as described in {@link ServerName}
@return the relative WAL directory name, e.g. <code>.logs/1.example.org,60030,12345</code> if
        <code>serverName</code> passed is <code>1.example.org,60030,12345</code>
hbase-server/src/main/java/org/apache/hadoop/hbase/wal/AbstractFSWALProvider.java