Our WP setup is a backend server that runs MySQL Master database, and some frontend servers each running a MySQL Slave. HyperDB is used to route frequent reads to a local db, and rare writes to the backend.
We recently switched from WPSC to W3TC. I was researching an issue with stale page cache, and browsed through plugin files, where I noticed a "dbcluster-config-sample.php" inside "ini" folder of the source. This file contains config sample very similar to that of HyperDB we're currently using.
To resolve a conflict of HyperDB's "db.php" with that of W3TC I had to modify the plugin code (two lines defining W3TC_INSTALL_FILE_DB and W3TC_ADDIN_FILE_DB in "/inc/define.php", and renaming "wp-content/db.php" to "db-cache.php".
Question: is W3TC capable of configuring the db to read from one database and write to another? How?