If you have to perform an out-of-disk sort, buy another hard disk and now it's not out-of-disk anymore. This will suffice for nearly any data set you would ever

If you have to perform an out-of-disk sort, buy another hard disk and now it's not out-of-disk anymore. This will suffice for nearly any data set you would ever need to sort. A 4 TB drive costs about $120, and you'll spend way more than that on software development and extra computers if you do distributed computing when you don't need to.