Frequent Database Corruptions

Running many WordPress installations on several different hosting services, I have found myself having to repair+optimize the databases every 1-2 weeks on many if not all the multisite installations. There seems to be little correlation between the amount of traffic a site receives and how often the database becomes corrupted.

I am blocking access to “wp-login.php” and “xmlrpc.php” so I don’t think the botnets are causing the problem but I don’t know what to look for.

Root domains may continue to work but WordPress becomes unable to resolve well-established subdomains. I have to activate a plugin to repair and optimize the database on the root domain and after doing that everything works fine again.

Any suggestions on what I can do to track down the problem OTHER than disabling all plugins will be appreciated. I can’t allow the sites to run without the plugins for 1-2 weeks just to see if it’s a plugin issue. Nearly all of the plugins have been updated at least once, some twice, and a couple several times over the past two months.