# Misc Tools

The misc package has various tools for splitting/merging indices, changing norms, finding high freq terms, and others.

## DirectIODirectory

{@link org.apache.lucene.misc.store.DirectIODirectory} is a Directory implementation that bypasses the OS's buffer cache (using direct IO) for any IndexInput and IndexOutput used during merging of segments larger than a specified size (default 10 MB). This avoids evicting hot pages that are still in-use for searching, keeping search more responsive while large merges run.

See this blog post for details.