[wp-hackers] Transitioning to Multi-site

[Otto]

On Mon, Aug 23, 2010 at 10:09 AM, Eric Mann <eric at eamann.com> wrote:
> So what steps should I follow to
>  1) Set up Multisite - I know how to install it, but how should I configure it
> considering I want to use it for separate domains, not sub-folders or
> sub-domains?
>  2) Move content - I assume the regular WP export-import process will work?
>  3) Map the domains to their new home on the new installation?

I had to do this myself. It's not hard, actually.

1. Set up a multisite install on one of the sites. One site has to be
the "master", and you cannot change its URL, so choose wisely. When
setting up the other "sub-sites", use a subfolder installation to do
it. They're easier and it frankly doesn't matter which you use in the
end result if you're doing domain mapping. See step 3.

2. Move the content from *one* domain to a new site in WP. I used the
import/export to do it. This works, but images and other things may
break along the way. So you're basically going to do this one site at
a time, and generally it's a pain. This is why you do it one site at a
time. The search/replace regex plugin is invaluable here, to fix all
the images that are going to break in your content (Multisite uses a
different method for storing uploaded files, and all attached files
have a url of http://example.com/files/whatever.jpg. The "files" has
an .htaccess rule to redirect that to the proper p;ace.

3. Using the Domain Mapping plugin, you'll be able to change that
subfolder URL into the domain URL (or frankly any URL.. this is why
the subdomain/subfolder choice is irrelevant, the domain mapping
plugin lets you pick any URL in the world to use, as long as you can
make that URL point to the WordPress installation). I wrote a tutorial
on how to do this:
http://ottopress.com/2010/wordpress-3-0-multisite-domain-mapping-tutorial/

In reality, you'll sort of perform steps 2 and 3 side by side, as you
have to import the content, fix the domain, then fix the broken image
links and such. It's not actually seriously time consuming once you do
it a couple of times. After three sites, you'll be a pro at it. Most
of the time is spent waiting for DNS changes to take effect.

If you have custom themes and such, then you'll need to put them on
the main site, enable them, then use them on the sub-sites. You can
make it so that only specific sites can see specific themes, if you
like. Unless this is open to the public, that's probably not
necessary.

4. Repeat steps 2 and 3 for each site. It's not actually that
terrible, and it's just as easy as moving a site to a new domain...
which ain't particularly simple either. But take it one site at a time
and you'll be alright.

-Otto