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Re: Mysterious drive access and battery life

On  17 Dec, this message from Mark Williams echoed through cyberspace:
> On Tue, 17 Dec 2002 16:47:35 -0800
> Michael Hope <michaelh@juju.net.nz> wrote:
>> 1.  Most accesses are due to updating the file access time.  Turning 
>> this off gets rid of alot of redundant writes.  To turn it off, add the 
>> 'noatime' flag to your fstab and either reboot or re-mount the 
>> partition.
>> 2.  On Ext2 and probably XFS you can use the noflushd daemon.  This 
>> changes the kernel operation so that dirty data isn't flushed to the 
>> hard disk unless the disk is running.  This could lead to lost data and 
>> doesn't work with Ext3 or Reiser.

Any journaling filesystem currently doesn't work with noflushd. I had
mine access the disk every five seconds with ext3.

> Thanks for your response! I added noatime to the relevant fstab line:
> /dev/hda11      /               ext2    errors=remount-ro,noatime       0       1

You're obviously running ext2; any other partitons?

> but the drive still clicks to life every now and then. This is no good! Will noflushd have any more luck than hdparm?

Look for proceses accessing the disk all the time.

Besides the usual suspects like syslog (adding a '-' in front of the
file name doesn't sync the disk on every write), I did the following:

- tune bdflush: add to /proc/sysctl.conf:

# Tune bdflush:
vm/bdflush = 95 5000 100 512 500 60000 30000 20 0

I don't remember what the values mean; just look them up in the man

- use devfs: thus accesses to device files don't go to the filesystem
  (think atime here...)

- since I have enough RAM, use tmpfs as /tmp:

# /etc/fstab: static file system information.
tmpfs           /tmp            tmpfs   size=50M,mode=1777              0 0

- put the pmud socket somewhere else than the default /etc/power/apm.
  This was being read all the time by asapm displaying bat status:


Obviously, you need to adapt any app that's reading this.

Hope this helps


Michel Lanners                 |  " Read Philosophy.  Study Art.
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email   mlan@cpu.lu            |
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