apache/druid · warning

Skipping deep storage directory kill: backslash not allowed

Error message

Skipping deep storage directory kill: backslash not allowed in path [%s]

What it means

constructHdfsDeletePath rejects relative paths containing a backslash ('\'), logging this warning and returning null. Backslashes are illegal in HDFS path components in this context and usually indicate a Windows-style or escaped path that doesn't belong in HDFS deep storage; deleting based on it would be unsafe.

Source

Thrown at extensions-core/hdfs-storage/src/main/java/org/apache/druid/storage/hdfs/HdfsDataSegmentKiller.java:191

  }

  /**
   * Construct a path to delete from HDFS. Returns null if the path is invalid.
   * Replicates how {@link HdfsDataSegmentPusher#pushToPath} handles ':', by replacing that with '_'.
   */
  @Nullable
  private Path constructHdfsDeletePath(String relativePath)
  {
    if (Strings.isNullOrEmpty(relativePath)) {
      log.warn("Skipping deep storage directory kill: relative path is empty");
      return null;
    }
    if (relativePath.charAt(0) == '/') {
      log.warn("Skipping deep storage directory kill: relative path must not be absolute, got [%s]", relativePath);
      return null;
    }
    if (relativePath.indexOf('\\') >= 0) {
      log.warn("Skipping deep storage directory kill: backslash not allowed in path [%s]", relativePath);
      return null;
    }
    for (String segment : StringUtils.splitPreserveAllTokens(relativePath, '/')) {
      if (segment.isEmpty() || "..".equals(segment)) {
        log.warn("Skipping deep storage directory kill: invalid path[%s]", relativePath);
        return null;
      }
    }

    if (storageDirectory == null) {
      log.warn("Skipping deep storage directory kill: storage directory not configured");
      return null;
    }

    final String hdfsRelativePath = relativePath.replace(':', '_');
    final String storageDirectoryString = storageDirectory.toString();
    final String sep = storageDirectoryString.endsWith(Path.SEPARATOR) ? "" : Path.SEPARATOR;
    return new Path(storageDirectoryString + sep + hdfsRelativePath);

View on GitHub (pinned to 9b90983fd2)

Solutions

1. Fix the segment path in the metadata store to use '/' separators
2. Re-push affected segments with a correctly configured (Linux-style path) pusher
3. Skip killing these segments manually via hdfs dfs -rm once you locate the real path

Example fix

// before
"path": "datasource\\interval\...\index.zip"
// after
"path": "datasource/interval/.../index.zip"

if (segmentPath.contains("\\")) {
  throw new IllegalArgumentException("segment path must use '/' separators: " + segmentPath);
}

static boolean usesPosixSeparators(String p) { return p != null && p.indexOf('\\') < 0; }

When it happens

Trigger: A DataSegment's relative loadSpec path contains '\' characters, e.g. segments produced with Windows file separators or double-escaped paths.

Common situations: Segments generated on Windows-based ingestion tooling, manually constructed segment JSON with escaped separators, or copying segment metadata between Windows and Linux clusters.

Understand the failure class

Background: "Invalid ... format", "must be in format X", "does not look like a ..." — invalid argument format errors across CLI tools and libraries — this error's family across 17 libraries.

Related errors

• Skipping deep storage directory kill: relative path is empty
• Skipping deep storage directory kill: relative path must not
• Skipping deep storage directory kill: invalid path[%s]
• Segment path [%s] does not exist
• Skipping deep storage directory kill: storage directory not

AI-assisted analysis of apache/druid@9b90983fd2 (2026-09-07). Data as JSON: /api/errors/fbee7421a78e3c5f. Report an issue: GitHub.