What directory structure should I use to avoid maxdir-size issues?

Applies to

• ONTAP 9
• Cloud Volumes ONTAP
• Maximum Directory size

Answer

The best way to reduce the performance effect in directories with large numbers of files is to spread files across more directories in the file system.

• Newer platforms offer more memory and CPU capacity, and AFF systems provide performance benefits for high-file-count environments.
• The maxdir-size value can be a concern when you are using flat directory structures, where a single folder contains millions of files at a single level.
• Folder structures where files, folders, and subfolders are interspersed have a low impact on maxdir-size.

There are several directory structure methodologies

• For the best performance, avoid flat directory structures in ONTAP if at all possible.
• Wide or deep directory structures work best, as long as the path length of the file or folder does not exceed NAS protocol standards. 

Directory Structure	Layout	Recommended
Flat directory structure A single directory with many files
Wide directory structure Many top-level directories with files spread across directories.
Deep directory structure Fewer top-level directories, but with many subfolders; files spread across directories.
If flat directory structures are unavoidable, pay close attention to the maxdir-size values for the volume and increase them as necessary. NFS path lengths are defined by the client OS. For information about SMB path lengths, see this Microsoft Dev Center link.

Additional Information

• Does deleting files in a directory cause the directory size to reduce?
• What are the performance impacts of changing the size of maxdir-size?
• ONTAP file and directory structure Resolution Guide
• FAQ - ONTAP maximum directory size (maxdir-size)