Manual talk:$wgHashedUploadDirectory

changing an existing configuration
You will receive following error (MW 1.9.2)

 Warning: imagecreatefrompng(E:\Programme\xampp\htdocs\w/images/1_GrafikTest_01_1024.png) [function.imagecreatefrompng]: failed to open stream: No such file or directory in E:\Programme\xampp\htdocs\w\includes\Image.php on line 1266

Warning: imagecopyresampled: supplied argument is not a valid Image resource in E:\Programme\xampp\htdocs\w\includes\Image.php on line 1274

Fatal error: imagepng [function.imagepng]: gd-png: fatal libpng error: Invalid number of colors in palette in E:\Programme\xampp\htdocs\w\includes\Image.php on line 1275

Moving to the system
Does anyone have a script which runs through the uploads dir and files existing images into this new structure? I have way too many images just in the image folder, but there does not seem to be a migration path. --ThePlaz 07:14, 10 March 2010 (UTC)

Script
Thanx to Platonides !!mediawiki-l/2010-April/033779.html Make a backup archive of the images folder first ! Btw. this script should not touch subdirectories you may use for some extension scripts.

Changes / manual work:

mkdir($folder, 0755, true); chown($folder, "www-data"); chgrp($folder, "www-data"); chown www-data:www-data *
 * You may have to modify permissions, e.g.
 * then manually fix the owner of the top level directories
 * Then get rid of the contents of the thumb subdirectory, except "archive" ? (thumbs subdirectories will be automatically re-generated when users access pages)
 * Finally make sure that the cashes you use are emptied, e.g. "TRUNCATE TABLE objectcache;" in the MySQL database and kill the files in the file-cache subdirectory.

What is the virtue of using hashed upload directories
The one-liner, "If true, use the /a/ab/foo.png directory structure." does not describe any virtues.

Given that this decision is best made before any images are uploaded to a newly created wiki, I think that this article should describe the pros and cons of specifying

Newcomers to MediaWiki installation and configuration will then be able to make a decision appropriate to the expected size and traffic for a new wiki. Najevi 17:40, 26 September 2010 (UTC)
 * Performance is the reason. Now the article also tells this:
 * ''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.
 * --88.130.88.189 16:11, 19 December 2014 (UTC)

Why "f/f8/" not "f/8/"?
Why is the second folder repeating the first character? --93.184.128.22 10:18, 26 April 2016 (UTC)