apache/hadoop · error · IOException

Folder {} already exists! Delete manually or provide another

Error message

Folder {} already exists! Delete manually or provide another (not existing) directory!

What it means

When `hdfs oiv` runs a text processor with `-t/--temp <dir>`, PBImageTextWriter caches parent/child metadata in LevelDB databases under that directory. The LevelDBMetadataMap constructor demands a directory that does not yet exist, so no stale LevelDB data can leak into this run; if the path already exists it refuses immediately.

Source

Thrown at hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/tools/offlineImageViewer/PBImageTextWriter.java:396

        super(CAPACITY);
      }

      @Override
      protected boolean removeEldestEntry(Map.Entry<Long, String> entry) {
        return super.size() > CAPACITY;
      }
    }

    /** Map the child inode to the parent directory inode. */
    private LevelDBStore dirChildMap = null;
    /** Directory entry map */
    private LevelDBStore dirMap = null;
    private DirPathCache dirPathCache = new DirPathCache();

    LevelDBMetadataMap(String baseDir) throws IOException {
      File dbDir = new File(baseDir);
      if (dbDir.exists()) {
        throw new IOException("Folder " + dbDir + " already exists! Delete " +
            "manually or provide another (not existing) directory!");
      }
      if (!dbDir.mkdirs()) {
        throw new IOException("Failed to mkdir on " + dbDir);
      }
      try {
        dirChildMap = new LevelDBStore(new File(dbDir, "dirChildMap"));
        dirMap = new LevelDBStore(new File(dbDir, "dirMap"));
      } catch (IOException e) {
        LOG.error("Failed to open LevelDBs", e);
        IOUtils.cleanupWithLogger(null, this);
      }
    }

    @Override
    public void close() throws IOException {
      IOUtils.cleanupWithLogger(null, dirChildMap, dirMap);
      dirChildMap = null;

View on GitHub (pinned to 2add963021)

Solutions

1. Delete the leftover directory and rerun: `rm -rf <tempdir>`
2. Use a unique path per run, e.g. `-t "$(mktemp -d)"` or -t /tmp/oiv-$(date +%s)
3. Drop -t entirely for images whose metadata fits in memory (the default keeps it in-heap)

Example fix

# before: fixed temp dir fails on the second run
hdfs oiv -p delimited -i fsimage -o out.csv -t /tmp/oivtmp
# IOException: Folder /tmp/oivtmp already exists!

# after: fresh dir every run
rm -rf /tmp/oivtmp
hdfs oiv -p delimited -i fsimage -o out.csv -t "$(mktemp -d)"

// before starting oiv with -t
Path tmp = Paths.get(tempPath);
if (Files.exists(tmp)) {
  throw new IllegalStateException(
      "temp dir " + tmp + " already exists; delete it or pick a fresh path");
}

When it happens

Trigger: Running `hdfs oiv -p delimited -t /path/dir` (or DetectCorruption with -t) when that directory already exists — typically the second run of a script with a fixed temp path, or a leftover from a crashed previous run.

Common situations: Cron jobs or scripts with hardcoded -t paths; reruns after a failure; leftover directories under /tmp.

Related errors

• bytes array length error. Actual length is {}
• InMemoryAliasMap location is null
• Unable to create aliasmap snapshot directory {newLevelDBDir}
• Cannot remove current alias map: ${aliasMapFile}
• Param op must be specified.

AI-assisted analysis of apache/hadoop@2add963021 (2026-08-22). Data as JSON: /api/errors/e8f80997afda0659. Report an issue: GitHub.