Manual:$wgLocalisationCacheConf

Details
Localisation cache configuration.

Associative array with keys:

The class to use. May be overridden by extensions. The location to store cache data. May be 'files', 'db', 'array' or 'detect'. ** If set to "array", data will be in PHP files that store static arrays. This is an experimental option. The class name for the underlying storage. If set to a class name, it overrides the "store" setting. Set this to true to disable cache updates on web requests. Use  instead.
 * class:
 * store:
 * If set to "files", data will be in CDB files in the directory specified by  .
 * This is significantly faster than storing data into the database thread>Thread:Project:Support desk/$wgLocalisationCacheConf performance: file or db storage?|(see discussion)
 * If set to "db", data will be stored to the database.
 * This is the fastest option when using PHP-FPM and OPcache (without ), because OPcache will store these arrays. In other configurations (HHVM or opcache.file_cache_only) this mode has no benefit over "files".
 * If set to "detect", files will be used if   is set, otherwise the database will be used.
 * storeClass:
 * storeDirectory: If the store class puts its data in files, this is the directory it will use. If this is false,   will be used.
 * manualRecache: