title: Suitable data storage backend for Erlang application when data doesn't fit memory
body: <p>I'm researching possible options how to organize data storage for an Erlang application. The data it supposed to use is basically a huge collection of binary blobs indexed by short string ids. Each blob is under 10 Kb but there are many of them. I'd expect that in total they would have size up to 200 Gb so obviously it cannot fit into memory. The typical operation on this data is either reading a blob by its id or updating a blob by its id or adding a new one. At each given period of day only a subset of ids is being used so the data storage access performance might benefit from in-memory cache. Speaking about performance - it is quite critical. The target is to have around 500 reads and 500 updates per second on commodity hardware (say on EC2 VM).</p>
  
  <p>Any suggestions what to use here? As I understand dets is out of question as it is limited to 2G (or was it 4G?). Mnesia probably out of question too; my impression is that it was mainly designed for cases when data fits memory. I'm considering trying EDTK's Berkeley DB driver for the task. Would it work in the above scenario? Does anybody have experience using it in the production in the similar conditions?</p>