/** Test replace datanode on failure. */
@Test
public void testReplaceDatanodeOnFailure() throws Exception {
final Configuration conf = new HdfsConfiguration();
// do not consider load factor when selecting a data node
conf.setBoolean(DFSConfigKeys.DFS_NAMENODE_REPLICATION_CONSIDERLOAD_KEY, false);
// always replace a datanode
ReplaceDatanodeOnFailure.write(Policy.ALWAYS, true, conf);
final String[] racks = new String[REPLICATION];
Arrays.fill(racks, RACK0);
final MiniDFSCluster cluster =
new MiniDFSCluster.Builder(conf).racks(racks).numDataNodes(REPLICATION).build();
try {
cluster.waitActive();
final DistributedFileSystem fs = cluster.getFileSystem();
final Path dir = new Path(DIR);
final int NUM_WRITERS = 10;
final int FIRST_BATCH = 5;
final SlowWriter[] slowwriters = new SlowWriter[NUM_WRITERS];
for (int i = 1; i <= slowwriters.length; i++) {
// create slow writers in different speed
slowwriters[i - 1] = new SlowWriter(fs, new Path(dir, "file" + i), i * 200L);
}
for (int i = 0; i < FIRST_BATCH; i++) {
slowwriters[i].start();
}
// Let slow writers write something.
// Some of them are too slow and will be not yet started.
sleepSeconds(3);
// start new datanodes
cluster.startDataNodes(conf, 2, true, null, new String[] {RACK1, RACK1});
cluster.waitActive();
// wait for first block reports for up to 10 seconds
cluster.waitFirstBRCompleted(0, 10000);
// stop an old datanode
MiniDFSCluster.DataNodeProperties dnprop =
cluster.stopDataNode(AppendTestUtil.nextInt(REPLICATION));
for (int i = FIRST_BATCH; i < slowwriters.length; i++) {
slowwriters[i].start();
}
waitForBlockReplication(slowwriters);
// check replication and interrupt.
for (SlowWriter s : slowwriters) {
s.checkReplication();
s.interruptRunning();
}
// close files
for (SlowWriter s : slowwriters) {
s.joinAndClose();
}
// Verify the file
LOG.info("Verify the file");
for (int i = 0; i < slowwriters.length; i++) {
LOG.info(
slowwriters[i].filepath
+ ": length="
+ fs.getFileStatus(slowwriters[i].filepath).getLen());
FSDataInputStream in = null;
try {
in = fs.open(slowwriters[i].filepath);
for (int j = 0, x; (x = in.read()) != -1; j++) {
Assert.assertEquals(j, x);
}
} finally {
IOUtils.closeStream(in);
}
}
} finally {
if (cluster != null) {
cluster.shutdown();
}
}
}
