So, pending getting a chance to test mrball's plugin, here's a quick 'how to' upgrade an old version of WPMU (one where 99% of files are in wp-inst) to a new one (where wp-inst doesn't exist).
1. Back-up, lots :)
2. Give yourself a couple of days for a site with over 10k users - allows for server slowdowns / bugs / it taking a bloody long time
3. Let your users know what's going down.
4. FTP the latest code into your root folder
5. Get your server admin (I guess if you;re following this you're about as smart as me :) to copy wp-inst/wp-content/blogs.dir to wp-content/ (doing this through cPanel or by FTP frigs up the file ownership bits)
6. Configure your new wp-config file and .htaccess file, my working ones look like this:
RewriteEngine On
RewriteBase /
# Rewrite http://www.domain.com to domain.com
RewriteCond %{HTTP_HOST} ^www\.(.*)
RewriteRule ^(.*) http://%1/$1 [R,L]
#uploaded files
RewriteRule ^(.*)?/?files/(.*) wp-content/blogs.php?file=$2 [L]
RewriteCond %{REQUEST_FILENAME} -f [OR]
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule . - [L]
RewriteRule ^([_0-9a-zA-Z-]+/)?(wp-.*) $2 [L]
RewriteRule ^([_0-9a-zA-Z-]+/)?(.*\.php)$ $2 [L]
RewriteRule . index.php [L]
&
<?php
// ** MySQL settings ** //
define('DB_NAME', 'wordpress'); // The name of the database
define('DB_USER', 'username'); // Your MySQL username
define('DB_PASSWORD', 'password'); // ...and password
define('DB_HOST', 'localhost'); // 99% chance you won't need to change this value
define('VHOST', 'yes');
$base = '/';
// double check $base
if( $base == 'BASE' )
die( 'Problem in wp-config.php - $base is set to BASE when it should be the path like "/" or "/blogs/"! Please fix it!' );
// Change the prefix if you want to have multiple blogs in a single database.
$table_prefix = 'wp_'; // example: 'wp_' or 'b2' or 'mylogin_'
// Change this to localize WordPress. A corresponding MO file for the
// chosen language must be installed to wp-includes/languages.
// For example, install de.mo to wp-includes/languages and set WPLANG to 'de'
// to enable German language support.
define ('WPLANG', '');
define( "WP_USE_MULTIPLE_DB", false );
/* Stop editing */
define('ABSPATH', dirname(__FILE__).'/');
require_once(ABSPATH.'wp-settings.php');
?>
7. Go login and call blogsite.org/wp-admin/upgrade.php
8. Go to site admin > Upgrade site and sit tight!
For me this has frequently got stuck at various points - from experience so far you've got to have a pretty well optimized SQL database, lots of patience and be willing to 'give it a few hours' if it stops working and try again... scientific huh :)
9. Make sure that you point to wp-signup.php rather than wp-newblogs.php.
10. Have a holiday!
I think that's it, have I missed anything really important (this is ofteen the case so don't go following these instructions without checking for further comments below).
Cheers, James
