This WordPress installation has become pretty large lately, with us hosting over 400 sites with over 900 users. When we need to make updates there is always the potential to break some of these sites, and due to the large number of them, it’s hard for us to make sure they all work.
Recently we’ve started doing “two-step upgrades” where we make the upgrades on a separate, identical server and ask our users to take a look at their blog-counterparts to make sure everything is still working correctly. We call this second server our “staging server”… and you can even access it here. This cuts down on the time it takes for us to perform WordPress upgrades which then allows us to get the next batch of upgrades out the door faster.