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.