* checkpointing, we should clear existing snapshottable directories"
*/
@Test
public void testCheckpoint() throws IOException {
MiniDFSCluster cluster = null;
SecondaryNameNode secondary = null;
try {
cluster = new MiniDFSCluster.Builder(conf).build();
cluster.waitActive();
secondary = new SecondaryNameNode(conf);
SnapshotManager nnSnapshotManager = cluster.getNamesystem().getSnapshotManager();
SnapshotManager secondarySnapshotManager = secondary.getFSNamesystem().getSnapshotManager();
FileSystem fs = cluster.getFileSystem();
HdfsAdmin admin = new HdfsAdmin(FileSystem.getDefaultUri(conf), conf);
assertEquals(0, nnSnapshotManager.getNumSnapshots());
assertEquals(0, nnSnapshotManager.getNumSnapshottableDirs());
assertEquals(0, secondarySnapshotManager.getNumSnapshots());
assertEquals(0, secondarySnapshotManager.getNumSnapshottableDirs());
// 1. Create a snapshottable directory foo on the NN.
fs.mkdirs(TEST_PATH);
admin.allowSnapshot(TEST_PATH);
assertEquals(0, nnSnapshotManager.getNumSnapshots());
assertEquals(1, nnSnapshotManager.getNumSnapshottableDirs());
// 2. Create a snapshot of the dir foo. This will be referenced both in
// the SnapshotManager as well as in the file system tree. The snapshot
// count will go up to 1.
Path snapshotPath = fs.createSnapshot(TEST_PATH);
assertEquals(1, nnSnapshotManager.getNumSnapshots());
assertEquals(1, nnSnapshotManager.getNumSnapshottableDirs());
// 3. Start up a 2NN and have it do a checkpoint. It will have foo and its
// snapshot in its list of snapshottable dirs referenced from the
// SnapshotManager, as well as in the file system tree.
secondary.doCheckpoint();
assertEquals(1, secondarySnapshotManager.getNumSnapshots());
assertEquals(1, secondarySnapshotManager.getNumSnapshottableDirs());
// 4. Disallow snapshots on and delete foo on the NN. The snapshot count
// will go down to 0 and the snapshottable dir will be removed from the fs
// tree.
fs.deleteSnapshot(TEST_PATH, snapshotPath.getName());
admin.disallowSnapshot(TEST_PATH);
assertEquals(0, nnSnapshotManager.getNumSnapshots());
assertEquals(0, nnSnapshotManager.getNumSnapshottableDirs());
// 5. Have the NN do a saveNamespace, writing out a new fsimage with
// snapshot count 0.
NameNodeAdapter.enterSafeMode(cluster.getNameNode(), false);
NameNodeAdapter.saveNamespace(cluster.getNameNode());
NameNodeAdapter.leaveSafeMode(cluster.getNameNode());
// 6. Have the still-running 2NN do a checkpoint. It will notice that the
// fsimage has changed on the NN and redownload/reload from that image.
// This will replace all INodes in the file system tree as well as reset
// the snapshot counter to 0 in the SnapshotManager. However, it will not
// clear the list of snapshottable dirs referenced from the
// SnapshotManager. When it writes out an fsimage, the 2NN will write out
// 0 for the snapshot count, but still serialize the snapshottable dir
// referenced in the SnapshotManager even though it no longer appears in
// the file system tree. The NN will not be able to start up with this.
secondary.doCheckpoint();
assertEquals(0, secondarySnapshotManager.getNumSnapshots());
assertEquals(0, secondarySnapshotManager.getNumSnapshottableDirs());
} finally {
if (cluster != null) {
cluster.shutdown();
}
if (secondary != null) {
secondary.shutdown();
}
}
}