We recently relaunched USCHO, U.S. College Hockey Online, http://www.uscho.com on WordPress 3.0.1 multisite after running it on a homegrown platform for over 10 years (and static HTML before that.) It's a relatively high volume site, on pace for about 100 million page views this year.
We have been isolating various bugs and getting rid of bad acting plugins. But one issue remains and we're stumped trying to find it. I'm wondering if it has to do with W3TC. Or how to determine it.
We have W3TC installed on the main site, plus on each of 23 other blogs which act either as separate blogs or as departments. For example, we have news and features on the main site, game recaps at /recaps, blogs for various college hockey leagues, etc. We're caching pages and queries on disk and objects in eaccelerator. We're using gzip compression and refreshing the main site on a 900-second interval and the rest at 3600. Caching seems to be working flawlessly.
Here's what is happening: periodically and without warning, the site switches from displaying the custom page template for the main blog and that page's content to a header and template for another blog and the latest posts for that blog. All of the other parts of the site end up with a jumble of wrong headers and templates. Restarting apache fixes the issue.
Is this something that has been seen before? Do we have something misconfigured? What more information should I provide or should I be looking for?
Overall we're thrilled with the performance of W3TC. It may not even be the issue. But we're stumped.