apache/hadoop · error · DiskErrorException

Directory is not readable: ${dir}

Error message

Directory is not readable: ${dir}

What it means

checkAccessByFileMethods rejects a storage directory whose FileUtil.canRead(dir) returns false, throwing DiskErrorException('Directory is not readable: <dir>'). The read bit on the directory entry (or ACLs) denies the daemon user the ability to list its contents, so the disk is treated as bad.

Source

Thrown at hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/DiskChecker.java:161

  }

  /**
   * Checks that the current running process can read, write, and execute the
   * given directory by using methods of the File object.
   * 
   * @param dir File to check
   * @throws DiskErrorException if dir is not readable, not writable, or not
   *   executable
   */
  private static void checkAccessByFileMethods(File dir)
      throws DiskErrorException {
    if (!dir.isDirectory()) {
      throw new DiskErrorException("Not a directory: "
          + dir.toString());
    }

    if (!FileUtil.canRead(dir)) {
      throw new DiskErrorException("Directory is not readable: "
                                   + dir.toString());
    }

    if (!FileUtil.canWrite(dir)) {
      throw new DiskErrorException("Directory is not writable: "
                                   + dir.toString());
    }

    if (!FileUtil.canExecute(dir)) {
      throw new DiskErrorException("Directory is not executable: "
                                   + dir.toString());
    }
  }

  /**
   * The semantics of mkdirsWithExistsCheck method is different from the mkdirs
   * method provided in the Sun's java.io.File class in the following way:
   * While creating the non-existent parent directories, this method checks for

View on GitHub (pinned to 2add963021)

Solutions

1. Add the read bit: chmod u+r <dir> (or chmod 755) as appropriate
2. chown the directory to the daemon user/group so the mode applies
3. Verify as the daemon user: sudo -u yarn ls <dir>
4. Check ACLs/getfacl for deny entries masking permissions

Example fix

# before
sudo chmod 300 /data/nm-local   # no read bit
# after
sudo chmod 755 /data/nm-local && sudo -u yarn ls /data/nm-local

import java.nio.file.*;
for (String dir : configuredDirs) {
  Path p = Paths.get(dir);
  if (!Files.isReadable(p)) {
    throw new IllegalStateException("directory not readable by " + System.getProperty("user.name") + ": " + dir);
  }
}

When it happens

Trigger: Directory owned by another user with mode 300/333 (no r); restrictive ACLs masking the daemon user; chmod operations during hardening that dropped the read bit.

Common situations: Dirs created by root then handed to the cluster without chown; security hardening scripts applying overly strict modes; shared volumes with group misalignment.

Understand the failure class

Background: Permission denied / not authorized / 403 Forbidden: access-control rejections when the caller lacks the required role, grant, or ownership — this error's family across 18 libraries.

Related errors

• Cannot create directory: ${dir}
• Directory is not writable: ${dir}
• Directory is not executable: ${dir}
• Not a directory: ${dir}
• Failed to delete ${file}

AI-assisted analysis of apache/hadoop@2add963021 (2026-08-22). Data as JSON: /api/errors/664a15980c09ec2d. Report an issue: GitHub.