apache/hadoop · error · IOException

${pmemDir} does not exist

Error message

${pmemDir} does not exist

What it means

Error "${pmemDir} does not exist" thrown in apache/hadoop.

Source

Thrown at hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/fsdataset/impl/PmemVolumeManager.java:323

      // Update maxBytes and cache capacity according to cache space
      // used by recovered cached files.
      usedBytesCounts.get(volumeIndex).setMaxBytes(maxBytes + usedBytes);
      cacheCapacity += usedBytes;
      usedBytesCounts.get(volumeIndex).reserve(usedBytes);
    }
    return keyToMappableBlock;
  }

  public void recoverBlockKeyToVolume(ExtendedBlockId key, byte volumeIndex) {
    blockKeyToVolume.put(key, volumeIndex);
  }

  @VisibleForTesting
  static File verifyIfValidPmemVolume(File pmemDir)
      throws IOException {
    if (!pmemDir.exists()) {
      final String message = pmemDir + " does not exist";
      throw new IOException(message);
    }
    if (!pmemDir.isDirectory()) {
      final String message = pmemDir + " is not a directory";
      throw new IllegalArgumentException(message);
    }

    File realPmemDir = new File(getRealPmemDir(pmemDir.getPath()));
    if (!realPmemDir.exists() && !realPmemDir.mkdir()) {
      throw new IOException("Failed to create " + realPmemDir.getPath());
    }

    String uuidStr = UUID.randomUUID().toString();
    String testFilePath = realPmemDir.getPath() + "/.verify.pmem." + uuidStr;
    byte[] contents = uuidStr.getBytes(StandardCharsets.UTF_8);
    RandomAccessFile testFile = null;
    MappedByteBuffer out = null;
    try {
      testFile = new RandomAccessFile(testFilePath, "rw");

View on GitHub (pinned to 2add963021)

Solutions

1. Create the configured pmem directory or correct the path in dfs.datanode.pmem.cache.dirs.
2. Ensure the pmem device is mounted (with DAX) at the expected location before starting the DataNode.

When it happens

Trigger: Pmem cache initialization when a configured pmem directory path does not exist on the host.

Common situations: See trigger scenarios.

AI-assisted analysis of apache/hadoop@2add963021 (2026-08-22). Data as JSON: /api/errors/622db583c4ae976e. Report an issue: GitHub.