Setting up a multi-site Drupal 6 installation with shared databases and single sign-on

Using the basic tutorial you've provided, it appears possible to share user profile information across all sites in the multisite instance. So just to clarify in layman's, you set up/install a new Drupal DB for each site you want to set up, but then configure it's settings to force the site to use a different database and table for users, yes? For sites that do not share the same TLD, while you cannot get the SSO to work (because of cookie security) the user login and user profile data (provided you're using the core profile setup) *will* be share across all sites?

Also -- and I'm assuming the answer here is yes -- if you would prefer to have a standalone site along side a set of sites that share user data that's as simple as NOT configuring that new site's settings to point to the shared user tables and instead just leave that site's settings stay default as it relates to the database prefix?

Thanks!
-michael

Great post! Bookmarked!
You can also make a version of this page for Windows users.
Thanks

Thank you v much for the detailed description. I am trying to decide which way to go for a drupal 6 multi-site config (basically, I need one domain, multi-sub domains, different content and structure with a shared user base that has permissions/roles configurable for each sub-domain).

From what I've read your solutions ends up with effectively a single "user" database with "content" db for each sub domain.

There appears to be quite an elegent solution here: http://drupal.org/node/201673

This uses table name prefixes (rather than separate databases). However, I cannot get it to work as when I come to install the second sub-domains install drupal tells me that it is already installed. As this guide is written for drupal 5 I'm assuming that this now doesn't work in drupal 6 and I need to opt for separate databases.

I'd be very grateful if you can save me hours more reading by telling me weather my assumption that I must opt for separate db's for drupal 6 is correct?

Many thanks,
Crom

Thank you so much for this explanation, it worked almost perfectly. But, on my hosting (doteasy, I hate them so much) I had to do something like this:

$db_prefix = array(
'default' => '',
'users' => '`drupal_ms_shared`.',
'sessions' => '`drupal_ms_shared`.',
'authmap' => '`drupal_ms_shared`.'
);

Apparently, I have to enclose the database name with the ` character

Thank you so much for putting this page up. I've been looking everywhere for how to share tables and have a single sign-on with a multi-site setup, and this is the first tutorial that gave enough information that I could follow. Just saying, as most places did, to use the $db_prefix was not enough -- I needed to understand what was being done with the database also. Again, thank you!!

Susan from Los Angeles

can you tell me how to setup drupal like above but with diffrent user and password?? example drupal_ms_1 with user1@localhost and drupal_ms_2 with user2@localhost
im newbies in drupal
thanks

Thanks Mike for the feedback... It's important to realize that if you do not include the profile_* tables in the shared database, users will have to create a new profile for each site. In my environment I left off those tables because I did not plan on using the Drupal Profile core modules, in favor of the Content Profile module which creates user profiles as nodes. To further complicate the situation, I was using the Domain Access module to shared nodes between the sites (including the profile nodes). Very good point, Mike!

-Eric