There is a nice short article on memory issue in R at http://www.matthewckeller.com/html/memory.html. If you use R to process large data, you might find it helpful.
– checking how much memory an object is taking;
– the memory limit of 32-bit R and 64-bit R;
– package designed to store objects on hard drives rather than RAM;
– memory garbage collection with gc(); and
– some tips to reduce memory fragmentation.