apache/hadoop · error · NotInMountpointException

getDefaultReplication on path `<f>' is not within a mount po

Error message

getDefaultReplication on path `<f>' is not within a mount point

What it means

ViewFileSystem.getDefaultReplication(Path) resolves the path through the mount table; a FileNotFoundException from resolve() (path not under any mount link) is translated into NotInMountpointException('getDefaultReplication on path ... is not within a mount point'). Replication is a property of the target HDFS, so viewfs cannot answer for unmounted paths.

Source

Thrown at hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/viewfs/ViewFileSystem.java:987

      InodeTree.ResolveResult<FileSystem> res =
        fsState.resolve(getUriPath(f), true);
      return res.targetFileSystem.getDefaultBlockSize(res.remainingPath);
    } catch (FileNotFoundException e) {
      throw new NotInMountpointException(f, "getDefaultBlockSize");
    } catch (IOException e) {
      throw new RuntimeException("Not able to initialize fs in "
          + " getDefaultBlockSize for path " + f + " with exception", e);
    }
  }

  @Override
  public short getDefaultReplication(Path f) {
    try {
      InodeTree.ResolveResult<FileSystem> res =
        fsState.resolve(getUriPath(f), true);
      return res.targetFileSystem.getDefaultReplication(res.remainingPath);
    } catch (FileNotFoundException e) {
      throw new NotInMountpointException(f, "getDefaultReplication");
    } catch (IOException e) {
      throw new RuntimeException("Not able to initialize fs in "
          + " getDefaultReplication for path " + f + " with exception", e);
    }
  }

  @Override
  public FsServerDefaults getServerDefaults(Path f) throws IOException {
    try {
      InodeTree.ResolveResult<FileSystem> res =
          fsState.resolve(getUriPath(f), true);
      return res.targetFileSystem.getServerDefaults(res.remainingPath);
    } catch (FileNotFoundException e) {
      throw new NotInMountpointException(f, "getServerDefaults");
    }
  }

  @Override

View on GitHub (pinned to 2add963021)

Solutions

1. Mount the directory in question, e.g. add fs.viewfs.mounttable.default.link.<name>=<target>
2. Point the replication query at a path that is already mounted (check with `hadoop fs -ls viewfs://cluster/`)
3. Add linkMergeSlash to cover the whole namespace: fs.viewfs.mounttable.default.linkMergeSlash=hdfs://nameservice1/
4. Catch NotInMountpointException and fall back to the target cluster's dfs.replication value

Example fix

// before
short rep = fs.getDefaultReplication(new Path("/staging")); // throws if /staging not mounted

// after
short rep;
try {
  rep = fs.getDefaultReplication(new Path("/staging"));
} catch (NotInMountpointException e) {
  rep = (short) conf.getInt("dfs.replication", 3);
}

// Ensure the replication query targets a mounted prefix
static boolean replicationPathSafe(Configuration conf, Path p) {
  return conf.get("fs.viewfs.mounttable.default.linkMergeSlash") != null
      || isMounted(conf, p); // see getDefaultBlockSize guard
}

try {
  short rep = fs.getDefaultReplication(p);
} catch (NotInMountpointException e) {
  short rep = (short) conf.getInt("dfs.replication", 3);
}

When it happens

Trigger: Calling getDefaultReplication(path) where path resolves to an internal mount-table directory ('/' or a parent of mounts such as /data when only /data/hdfs is linked), or where the path prefix matches no configured fs.viewfs.mounttable.default.link.* entry.

Common situations: Output committers and writers that ask for default replication of the output directory when the output dir is not in the mount table; incomplete mount tables after a viewfs cutover; tests using viewfs URIs with a minimal config.

Related errors

• ViewFs: Non absolute mount name in config:{src}
• Path {nextInode.fullPath} already exists as link
• Path {strB} already exists as dir; cannot create link here
• Unexpected mount table link entry '{key}'. Use linkMergeSlas
• ViewFs: Cannot initialize: Invalid entry in Mount table in c

AI-assisted analysis of apache/hadoop@2add963021 (2026-08-22). Data as JSON: /api/errors/ae86cb11bd4ba8f3. Report an issue: GitHub.