Found the following link that talks about wafl.dir.size.max at netapp:
The main thing to take from it is:
Never increase maxdirsize beyond 3% of physical memory.A volume with 30.72MB maxdirsize can hold up to 416808 CIFS files or 1,006,632 NFS files.
Memory * max files per wafl_dir_block / conversion = # of files
31457.28KB * 128 wafl_name_dir_entires * 1MB/4KB = 1,006,632 nfs files
With maxdirsize of 31,457, a directory can hold 1,006,632 files without CIFS enabled.
#The most important point is to avoid a high number of files in a single
directory. Create sub-directory structures and place files at
the bottom of the directory tree. Less than 1000 files per directory is ideal.
# Avoid deep directory structures. A depth of less than 5 is ideal, anything above 8 or 9 results in poor performance.
All around great info! I used to just estimated how big I want to make the max.dir.size (10MB) and now I can with enthusiasm be defiant in my choice.