Keeping all data in RAM and just saving changes to a log file is a great architecture. It is a pity that the current "hip" tools/models for web development impo

Keeping all data in RAM and just saving changes to a log file is a great architecture. It is a pity that the current "hip" tools/models for web development impose unnecessary cost for using it. The problem is that the Ruby / Python / PHP stacks typically have one process per request, and they do not share memory. When you use memcached in such environment, it is a separate process and communication with it is rather slow - it involves marshaling the data, which would not be necessary if all requests were just threads in a single address space.You don't have this problem if you use Java/C++. I have used with some success a huge mmaped file as persistent memory to store my data. It's not exactly using disc as sequential device, that depends on the application and data locality. There are just a few tools available to support that scheme.