private int doRun() throws IOException {
NamenodeProtocol proxy = createNNProtocolProxy();
NamespaceInfo nsInfo;
try {
nsInfo = proxy.versionRequest();
} catch (IOException ioe) {
LOG.fatal("Unable to fetch namespace information from active NN at " +
otherIpcAddr + ": " + ioe.getMessage());
if (LOG.isDebugEnabled()) {
LOG.debug("Full exception trace", ioe);