I have created a sharded cluster for use with GridFS.

I would like to use a hashed shard key for the chunks to ensure the data is uniformly distributed across the cluster. When I try to use the filemd5 command to validate the files I receive an error saying the collection has to be indexed on the {{

or

}}.

mongos> db.gridfs.chunks.runCommand( { filemd5 : ObjectId("51b535788544eb45b4cdaab5"), root : 'gridfs' } )
{
    "ok" : 0,
    "errmsg" : "GridFS fs.chunks collection must be sharded on either {files_id:1} or {files_id:1, n:1}"
}

I think the set of acceptable indexes should be updated to include the hashed type.

The stats() for the chunks collection is attached.