Manual:$wgMessageCacheType

Details
Message cache setting.

Here are the available CACHE constants, as defined in Defines.php


 * CACHE_ANYTHING - Use anything, as long as it works
 * CACHE_NONE - Do not cache
 * CACHE_DB - Store cache objects in the DB
 * CACHE_MEMCACHED - , must specify servers in 
 * CACHE_ACCEL - eAccelerator, mmTurck, APC or XCache, whichever is available
 * As of MediaWiki 1.18, thread>Thread:Project:Support desk/Caching with eAccelerator|current versions of eAccelerator no longer work. In MediaWiki 1.19 it will be removed.


 * CACHE_DBA - Use PHP's DBA extension to store in a DBM-style database

Note
If you set  then the values for  and $wgMessageCacheType will inherit it. You do not need to set those variables unless you plan on doing something very advanced.