Home > Storage > PowerScale (Isilon) > Product Documentation > Storage (general) > PowerScale OneFS Best Practices > Directory structure and layout
In general, it is more efficient to create a deep directory hierarchy that consolidates files in balanced subdirectories than it is to spread files out over a shallow subdirectory structure. Although the recommended maximum file limit per directory is one million, a best practice is to constrain the number of files in any one directory to one hundred thousand. A maximum of 100,000 directories per directory is also recommended. OneFS dynamically allocates new inodes from free file system blocks.
The key for file and directory layout always revolves around balance. The goal should be for a directory tree structure and is file contents to be as uniform as possible.
The OneFS protocol daemons, such as the input-output daemon (lwio), may impose additional constraints on the number of files that a node can have open. The protocol daemons typically impose such constraints because the kernel places limits on per-process memory consumption.