anchor.diff:  == Store
   
   The store module allows you to control how index data is stored and accessed on disk.
  +
  +NOTE: This is a low-level setting. Some store implementations have poor
  +concurrency or disable optimizations for heap memory usage. We recommend
  +sticking to the defaults.
   
   [float]
   [[file-system]]
  
positive.code: The Simple FS type is a straightforward implementation of file system
  storage (maps to Lucene `SimpleFsDirectory`) using a random access file.
  This implementation has poor concurrent performance (multiple threads
  will bottleneck). It is usually better to use the `niofs` when you need
  index persistence.
  
  [[niofs]]`niofs`::
  
  The NIO FS type stores the shard index on the file system (maps to
  Lucene `NIOFSDirectory`) using NIO. It allows multiple threads to read
  from the same file concurrently. It is not recommended on Windows
  because of a bug in the SUN Java implementation.
  
  [[mmapfs]]`mmapfs`::
  
  
negative.code: PUT /my_index
  {
    "settings": {
      "index.store.type": "hybridfs"
    }
  }
  ---------------------------------
  