The store module allows you to control how index data is stored and accessed on disk.

File system storage typesedit

There are different file system implementations or storage types. By default, elasticsearch will pick the best implementation based on the operating environment.

This can be overridden for all indices by adding this to the config/elasticsearch.yml file: niofs

It is a static setting that can be set on a per-index basis at index creation time:

PUT /my_index
  "settings": {
    "": "niofs"

This is an expert-only setting and may be removed in the future

The following sections lists all the different storage types supported.

Default file system implementation. This will pick the best implementation depending on the operating environment: simplefs on Windows 32bit, niofs on other 32bit systems and mmapfs on 64bit systems.
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.
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.
The MMap FS type stores the shard index on the file system (maps to Lucene MMapDirectory) by mapping a file into memory (mmap). Memory mapping uses up a portion of the virtual memory address space in your process equal to the size of the file being mapped. Before using this class, be sure you have allowed plenty of virtual address space.
default_fs [5.0.0] Deprecated in 5.0.0. The default_fs store type is deprecated - use fs instead
The default type is deprecated and is aliased to fs for backward compatibility.