I have a little confusion here on how redis do the job in Magento exactly.
When redis and magento cache management enabled, are both running and work at the same time? Or, redis override all the magento cache management function at all?
There are important points to know about cache backends. There are two level of cache : the fast cache and the slow cache backend.
Those backends serves different purposes, but there are key points to remember:
The fast backend stores “unstructured” data and thus can use several type of backends like APC, File, Database, Memcached, Redis, Xcache, etc.
The slow backend need a structured storage. This means that APC, Xcache, Memcached and other unstructured backend cannot be used. Stays Redis, File, Database.