[wp-hackers] multiple databases vs different database prefixes

[Brian Layman]

I agree with Jacob. With the old school b5media, we'd done it both ways.
While running separate installations of WordPress, we'd peaked at around 317
live blogs.  What that does is create a nightmare for file handling on your
servers. Let's guess at WordPress having 800 files when looking at themes
and plugins combined.  Running separate WP instances, that's roughly 800 *
300 = 240,000 different files the server has to deal with and hopefully
cache rather than load off of the hard drives.  Compare that with a
multi-site install - 800 files total.  Obviously from a file perspective, a
singe directory is easier to deal with. We'd even experimented using
soft-links to serve the same files and get around this before WPMU had
matured.   Also of consideration is what will happen when you update to a
newer version of wordpress.  NSF will take lots of resources when it tries
to sync up all of the changes across all of the servers.

The database faces similar issues. Creating a single database with 11 * 300
= 3300 tables can cause its own set of headaches as a "show tables" in a
random plugin causes your whole site to pause.  Mike & Scribu nailed it.
HyperDB will become your close personal friend.

Not using MS means you can have each blog admin/author be truly in charge of
their site and opens up configurations options blocked by the nature of MS
and eliminates some security concerns as well.  I imagine that came into
play in your decision.

Backups regimes are easy enough. You'll want to create a table of installs
etc you can run off of. That way you'll know all the install directories and
database names. And then you can just iterate them. I have my own scripts
you could modify for this purpose if you like.

lol you're making me all nostalgic now...
______________________________________________
Brian Layman
eHermits, Inc.
TheCodeCave.com / eHermitsInc.com / twitter.com/BrianLayman /
facebook.com/eHermit