Manual:$wgHashedUploadDirectory/ja

Details
If, uploaded files will be distributed into sub-directories of  based on the first two characters of the md5 hash of the filename. (e.g. ) Creation of such subdirectories is handled automatically. This is used to avoid having too many files in one folder because some filesystems don't perform well with large numbers of files in one folder.

The algorithm for that is based on a md5 of the name, the first hex character is used for the first directory, then the first two characters are used for the subdirectory.


 * → md5 of filename =  → f + f8 = /images/f/f8/Foo.png

If, all images are uploaded in  itself. (e.g. )

This parameter should not be changed after the first image or file has been uploaded (or else you will need to move all previous uploaded pictures). It will result in PHP errors (see the discussion page) if articles with the old logic try to find their pictures, since the image path is calculated and not stored in the database.

If you set, this variable will be ignored.