I have the following setup:
Magento community 1.9.2
1 x Ec2 frontend, running Litespeed Webserver, php run through Litespeed's Php implementation - LSPHP, sort of like fast-cgi used in Nginx
1 x RDS server for database
I just configured 1 x Elasticache (Redis node)
I have configured my local.xml to send session and backend cache to the Redis database.
I can see the cache store is filling up, plus the speed difference is notable (plus no files in cache and session folders)
My three questions are:
do I still need to install php-Redis extension on the frontend web-server for php? (Considering it's all working) I can't seem to work out what it's used for ?
Is there a way to know how much space I'll need ? My file store cache was less than 50mb yet my redis cache is already used 300mb
What happens if the store fills up? Does it delete old session caches ? Or does the site start having issues on the front end (like carts being emptied?)