apache/hadoop · error · IOException

Could not create directory ${curDir}

Error message

Could not create directory ${curDir}

What it means

SecondaryNameNode.ensureCurrentDirExists() verifies that the current/ subdirectory exists in every checkpoint storage directory before merging; if it does not exist and mkdirs() fails, an IOException with the concrete path is thrown and the checkpoint aborts. Unlike the startup checks, this fires mid-checkpoint when storage becomes unwritable between checkpoints.

Source

Thrown at hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/SecondaryNameNode.java:1052

    void setMergeError() {
      mergeErrorCount++;
    }

    void clearMergeError() {
      mergeErrorCount = 0;
    }
 
    /**
     * Ensure that the current/ directory exists in all storage
     * directories
     */
    void ensureCurrentDirExists() throws IOException {
      for (Iterator<StorageDirectory> it
             = storage.dirIterator(); it.hasNext();) {
        StorageDirectory sd = it.next();
        File curDir = sd.getCurrentDir();
        if (!curDir.exists() && !curDir.mkdirs()) {
          throw new IOException("Could not create directory " + curDir);
        }
      }
    }

    void deleteTempEdits() throws IOException {
      FilenameFilter filter = new FilenameFilter() {
        @Override
        public boolean accept(File dir, String name) {
          return name.matches(NameNodeFile.EDITS_TMP.getName()
              + "_(\\d+)-(\\d+)_(\\d+)");
        }
      };
      Iterator<StorageDirectory> it = storage.dirIterator(NameNodeDirType.EDITS);
      for (;it.hasNext();) {
        StorageDirectory dir = it.next();
        File[] tempEdits = dir.getCurrentDir().listFiles(filter);
        if (tempEdits != null) {
          for (File t : tempEdits) {

View on GitHub (pinned to 2add963021)

Solutions

1. Check free space and mount health on every checkpoint volume (df -h <dir>) and clear space or remount rw
2. Fix ownership/permissions on <checkpoint.dir>/current so the 2NN user can create it
3. Remove any stray regular file named 'current' blocking directory creation
4. Restart the SecondaryNameNode after repair; the next checkpoint cycle will recreate current/

Example fix

# before: current/ cannot be created
$ ls -l /data/2nn/checkpoint
total 0
-rw-r--r-- 1 root root 0 current   # regular file shadowing the dir
# after
$ sudo rm /data/2nn/checkpoint/current && sudo -u hdfs hdfs secondarynamenode

// before relying on checkpoint storage at runtime
for (Iterator<StorageDirectory> it = storage.dirIterator(); it.hasNext();) {
  File cur = it.next().getCurrentDir();
  if (!cur.exists()) {
    File parent = cur.getParentFile();
    if (!parent.canWrite()) {
      throw new IOException("Cannot create " + cur + ": parent not writable");
    }
  }
}

// the Checkpointer loop already catches IOException per cycle and retries at the
// next checkpoint interval — inspect cause, repair the volume, let it retry:
try {
  secondaryNameNode.doCheckpoint();
} catch (IOException e) { // includes "Could not create directory <curDir>"
  LOG.warn("Checkpoint failed, will retry: {}", e.getMessage());
}

When it happens

Trigger: sd.getCurrentDir() returns <checkpoint.dir>/current which is absent, and File.mkdirs() returns false — parent not writable, disk full, read-only filesystem remount, or a plain file named 'current' already occupying the path.

Common situations: Checkpoint disk fills up or goes read-only (failing disk, NFS soft-mount trouble) while the 2NN keeps running; permissions changed after a security hardening pass; a partially formatted directory left over from a crashed run.

Related errors

• checkpoint directory does not exist or is not accessible.
• Couldn't find image file at txid ${sig.mostRecentCheckpointT
• Cannot create directory {curDir}
• Image transfer servlet at " + url + " failed with status cod
• Unable to download to any storage directory

AI-assisted analysis of apache/hadoop@2add963021 (2026-08-22). Data as JSON: /api/errors/e6a64a5d467b37ff. Report an issue: GitHub.