Adam Gibson wrote:
I am rather surprised that this has not been dealt with by now. Why mess with the currently cached information when you know that the files being read will be many times more than your memory/swap space and will only need to be read once.
It's possible to use the flag
O_DIRECT
http://homepages.cwi.nl/~aeb/linux/man2html/man2/open.2.html
It's up to your backup program if it wants to use the flag or not, but it is there.
-Andy