In an ordinary WordPress website, the site administrator controls the themes and
plug-ins the site uses. But in a multisite network, this approach would be too risky,
because a single malicious plug-in could steal sensitive data from any site in the
network, or wipe out the database of your entire network.
Instead, multisite networks use a more disciplined system. You, the network administrator,
can pick the themes and plug-ins you want to allow. Site administrators can
then choose from the options you set.
A typical multisite installation begins with a few standard themes (such as Twenty
Twelve, Twenty Thirteen, and Twenty Fourteen), but only one of them is network
enabled (Twenty Fourteen). That means Twenty Fourteen is the only theme the sites
in your network can use. In fact, site administrators can’t see the other themes at all.
You can also enable a theme for some sites but not others, although it’s awkward.
First, make sure your theme isn’t network-activated. Then choose Sites→All Sites
and click the Edit link under the site where you want to apply the theme. When the
Edit Site page appears, click the Themes tab. In the list of disabled themes, click
Enable next to the ones you want to add.
The process for installing plug-ins is similar but subtly different. First, choose
Plugins→Add New and then search for the plug-in you want. When you find it, click
Install Now. Now you have a choice•
• Make the plug-in optional (don’t do anything).
• Activate the plug-in for every site.
GEM IN THE ROUGH
Setting a Storage Limit
Themes and plug-ins aren’t the only restrictions that come into
play on a multisite network. You can also set storage limits to
restrict how many pictures, documents, and other files people
can upload to their sites. These settings prevent space hoggers
from swallowing gigabytes of hosting room, leaving your web
server starved for space.
Ordinarily, your network has no site restrictions. To put
one into effect, choose Settings→Network Settings on the
network administration dashboard. Scroll down to the “Site
upload space” heading and switch on “Limit total size of files
uploaded.” That caps the amount of space for posts, pages,
pictures, and uploaded files on a site to 100 MB. However,
you can type in whatever maximum you want. You can also
change the “Max upload file size” to set the maximum size of
an individual file (usually 1.5 MB).
Site administrators can use a dashboard to keep an eye on the
size of their sites. Choose Dashboard→Home, and look at the
“At a Glance” box. At the bottom, you find the key details: the
maximum size allotment, the current size of the site, and the
percentage of space used so far.