David Holland wrote: > There is at least one known structural problem where atime/mtime > updates do not get applied to buffers (but are instead saved up > internally) so they don't get written out by the syncer. > > We believe this is what causes those unmount-time writes, or at least > many of them.
I understand the delayed atime writes were to added to reduce the number of times a laptop harddisk spins up. I've often wondered if a simple sysctl could be added to control this. Unmounting my /home on my main machine takes approximately a minute. My ups-nut script does sync ( cd /home; umount /home ) sync as soon as it gets an on-battery event so that hopefully the actual shutdown if needed happens quickly. Cheers, Simon.