I have two file systems of the same type (ext3) and mounted with the same options (rw, relatime, data=ordered).
On one of them, reading a file whose atime is older than 24 hours updates the atime. On another, it doesn't, even if the atime is several months old. Those file systems are local, which exonerates NFS, and on the same host, which means it's not just different software versions. Does that ring a bell ? -- André Majorel <http://www.teaser.fr/~amajorel/> bugs.debian.org, a spammer's favourite.