Re: Linux kernel - and regular sync'ing?

From: Alan Cox (alan@lxorguk.ukuu.org.uk)
Date: Thu Mar 08 2001 - 07:09:51 EST


> at irregular intervals of 10-30 seconds, most likely calls to sync, so
> that the disk never gets to sleep for long. I've followed advice in the
> various HOWTO's, e.g. modifying the line "ud::once:/sbin/update" in
> /etc/inittab to only sync once an hour, to no avail. Watching "top", it

Thats actually I think poor advice - it wont help and its asking to lose data

> Can you offer me any advice? Any tweeks I can make to tell the system
> that sync'ing only once every 5 minutes is o.k.?

You machine can sync continually - providing it isnt writing data. The real
question is not 'why is it syncing' but 'what is it syncing'.

The normal answer is file access times, and you can turn those off with the
noatime mount option.

To quote the linux on palmax page

   For startup my /etc/rc.d/rc.local contains the following lines.
mount -o remount,rw,noatime /
/sbin/hdparm -S 15 /dev/hda

   The "noatime" setting turns off the writing back of 'last accessed'
   times to files. This means reading/opening files does not cause disk
   wakeups. The hdparm -S 15 command sets the disk to spin down after 1
   minute 15 seconds (you can play with the value).
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