On a GNU/Linux system you actually write for each read because the filesystem tracks the last access time for each file. While this is potentially useful data (e.g. HSM) in many cases it's useless and the file system runs slower as a result. There are a couple of ways to turn this off, depending on how precise control you need. On a file-by-file basis you can chattr +A file_name each file, or for the whole filesystem you can add noatime to the list of filesystem parameters in /etc/fstab. I've seen this documented in a few places, most recently http://www.linuxjournal.com//article.php?sid=5840

GNU/Linux: is IDE DMA turned on? Use hdparm to check.

-- TobyCabot - 25 Feb 2002