apache/hadoop · error · UnsupportedOperationException

{} doesn't support createSnapshot

Error message

{} doesn't support createSnapshot

What it means

FileSystem.createSnapshot(Path, String) is optional; the base class throws UnsupportedOperationException with getClass().getSimpleName() + " doesn't support createSnapshot". Snapshots are an HDFS NameNode feature: only DistributedFileSystem (and pass-through wrappers: ViewFileSystem, ChRootedFileSystem, FilterFileSystem when the inner FS supports it) plus WebHdfsFileSystem override it. Local and object-store filesystems throw.

Source

Thrown at hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/FileSystem.java:3103

   * @return the snapshot path.
   * @throws IOException IO failure
   * @throws UnsupportedOperationException if the operation is unsupported
   */
  public final Path createSnapshot(Path path) throws IOException {
    return createSnapshot(path, null);
  }

  /**
   * Create a snapshot.
   * @param path The directory where snapshots will be taken.
   * @param snapshotName The name of the snapshot
   * @return the snapshot path.
   * @throws IOException IO failure
   * @throws UnsupportedOperationException if the operation is unsupported
   */
  public Path createSnapshot(Path path, String snapshotName)
      throws IOException {
    throw new UnsupportedOperationException(getClass().getSimpleName()
        + " doesn't support createSnapshot");
  }

  /**
   * Rename a snapshot.
   * @param path The directory path where the snapshot was taken
   * @param snapshotOldName Old name of the snapshot
   * @param snapshotNewName New name of the snapshot
   * @throws IOException IO failure
   * @throws UnsupportedOperationException if the operation is unsupported
   *         (default outcome).
   */
  public void renameSnapshot(Path path, String snapshotOldName,
      String snapshotNewName) throws IOException {
    throw new UnsupportedOperationException(getClass().getSimpleName()
        + " doesn't support renameSnapshot");
  }

View on GitHub (pinned to 2add963021)

Solutions

  1. Probe capability first: fs.hasPathCapability(dir, CommonPathCapabilities.FS_SNAPSHOTS) or fs instanceof DistributedFileSystem
  2. On HDFS, also allow snapshots on the directory first (hdfs dfsadmin -allowSnapshot <dir>) — a disabled snapshot dir yields a different, server-side error
  3. Catch UnsupportedOperationException and fall back to a copy-based backup (distcp) for stores without snapshots
  4. On object stores, use store-native versioning/bucket snapshots instead of the FileSystem API

Example fix

// before
Path snap = fs.createSnapshot(backupDir, "nightly-1");
// UnsupportedOperationException: LocalFileSystem doesn't support createSnapshot

// after
if (fs.hasPathCapability(backupDir, CommonPathCapabilities.FS_SNAPSHOTS)) {
  Path snap = fs.createSnapshot(backupDir, "nightly-1");
} else {
  LOG.warn("Snapshots unsupported on {}, falling back to distcp", fs.getUri());
  copyBackup(backupDir);
}
Defensive patterns

Strategy: try-catch

Validate before calling

import org.apache.hadoop.fs.CommonPathCapabilities;

if (fs.hasPathCapability(backupDir, CommonPathCapabilities.FS_SNAPSHOTS)) {
  Path snap = fs.createSnapshot(backupDir, "nightly-1");
}

Type guard

static boolean supportsSnapshots(FileSystem fs) {
  return fs instanceof DistributedFileSystem;
}

Try / catch

try {
  fs.createSnapshot(dir, name);
} catch (UnsupportedOperationException e) {
  // class named in e.getMessage() has no snapshot support: fall back to copy-based backup
}

Prevention

When it happens

Trigger: Calling fs.createSnapshot(dir, name) on LocalFileSystem (file://), S3A, ABFS, GCS, or HarFileSystem; snapshot/backup tooling invoked with the wrong fs.defaultFS; ViewFileSystem mounts whose target is not HDFS.

Common situations: Backup or rollback tooling written for HDFS and run in local unit tests; ops scripts pointed at the wrong cluster/scheme after config drift; distcp/Hive pipelines that snapshot before bulk changes.

Related errors

AI-assisted analysis of apache/hadoop@2add963021 (2026-08-22). Data as JSON: /api/errors/85aeafe9ad949ae2. Report an issue: GitHub.