I recently switched a store cache and session backend to Redis 3.0.3. I used the Cm_Cache_Backend_Redis and Cm_RedisSession extensions and the example configs provided. It works as expected and Redis stores the sessions and cache in 2 separate DB's. However, the site gets intermittent Magento 503 service unavailable errors (as reported by customers and observed by loading several pages at once). If I disable the extensions and go back to the standard file session_save's the problem goes away and can no longer be reproduced.
Is there some tuning that needs to be done to Redis to handle higher volume? Has anyone else every experienced this?