In message <19990207164950.A17923@pyy.jmp.fi>
  Jukka Marin <jmarin@pyy.jmp.fi> writes:
> Yes, I know what update is and why it does what it does.  What I didn't know
> was why anything was "flushed to disk" when no data were being written to any
> file.  The answer is that sync() updates the disk superblock timestamps
> even when no buffers are actually flushed to disk.  So, as far as I
> understand, using async mount is currently the only way to keep the disk
> sleeping.

No, it's inode meta-data (file atimes and device mtimes) that's being
flushed to disk. This is my /etc/apm/battery (see apm(8)):

#!/bin/sh

mount -u -o noatime,nodevmtime /
mount -u -o noatime /usr
mount -u -o noatime /var
echo "atactl wd0 setstandby 5" > /etc/apm/atacfg
. /etc/apm/atacfg

This works great for me (disk only spins up "when it has to"). I
really don't want to run without update or with file systems mounted
async.

Also check out http://www.netbsd.org/Documentation/power-mgmt/index.html

(Hmm, BTW. I've hacked apmd only to call /etc/apm/battery once for a
change of power mode. Before, it called /etc/apm/battery for each APM
event, which sucks on my Thinkpad 760 (one event per percent battery
used). Patches available on request (I will send-pr them sometime).)

-- 
Michael Eriksson <eramer@era-t.ericsson.se>
NO CARRIER