I am designing the backend of an ios app. I will have one database server, one application server and a separate cache server running memcached. For the cache server I can either run amazon elastic cache or have a amazon ec2 running memcached. What I am confused about is, how much cache does amazon ec2 have?
Suppose I want to use t1.micro type cache node of the amazon elastic cache. Amazon says it has 213 MB memory which I assume is the cache memory (though this is abnormally large for cache).
But if I want to use t1.micro ec2 as my cache server and run memcached in it, amazon says it has 613 MB of memory which I assume is the RAM. So what is the cache size of t1.micro (or in general any) amazon ec2 instance.
You are talking about memory available to the instance, memcached can be configured to use as much or as little memory as you want it to. If your application caching needs are still small, you might be able to do all the caching on the application server.
On a micro instance you have 613 MB of memory total. If you want memcached to behave effectively, you need to keep the entire application in memory. Being that some of the memory is needed to run the system, you probably have only about 213MB that you can effectively use to run memcached. Use too much, and it will push some of the memory into swap, and slow down the system.