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Date: | Sat, 15 Mar 2008 18:06:26 +0200 |
Content-Type: | text/plain |
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Andrea wrote:
> Hi all,
>
> I'm writing to report that I have detected the "unload cycle bug" while
> running SL5.1 on my laptop. This "bug" has received some attention
> months ago when it was found in Ubuntu¹ and consequently featured on
> Slashdot².
>
>
> ----- SUMMARY -----
>
> Some hard disk manufacturers ship their drives - especially laptop
> drives - preset with some aggressive power saving settings. These
> settings cause the hard disks to park their heads after a very short
> inactivity time.
>
> This hectic parking/deparking activity dramatically shortens the disk's
> life.
>
> Said manufacturers apparently take for granted that the OS will set more
> sensible power saving defaults for the hard disk. Linux distros often
> don't do this. So it's not exactly a "bug", rather an omission (even
> though it can be argued that this is not really "Linux's fault").
>
>
> ----- DIAGNOSIS -----
>
> The continued parking/deparking is typically easier to detect on a
> laptop, where you might hear periodic "clicks" coming from the hard
> disk.
>
> A more reliable way is to watch the output of the following `sh` command
> line, to be issued as root while your system is AC powered (as opposed
> to battery powered) and not performing disk-intensive tasks:
>
> while true;do smartctl -a /dev/hda|grep Load_Cycle_Count;sleep 120;done;
>
> If the last number is constantly increasing every 1 or 2 lines, your
> system is affected.
>
>
> ----- A SOLUTION -----
>
> The command:
>
> hdparm -B254 /dev/hda
>
> changes the primary drive's (/dev/hda) power settings to "almost never
> park heads". A lower number *might* be desired when running on battery,
> and an ideal solution would include a way to change that number
> according to power source (I don't know yet how to do this).
>
> For the moment, I suggest that the above command be put
> into /etc/rc.local to make sure it is executed at boot.
>
>
> Best regards,
> Andrea Remondini
>
>
>
>
> ----- NOTES -----
>
> ¹ <https://bugs.launchpad.net/ubuntu/+source/acpi-support/+bug/59695>
> ² <http://hardware.slashdot.org/article.pl?sid=07/10/30/1742258>
This doesn't seem to work on my desktop system:
[root@localhost ~]# while true; do smartctl -a /dev/hdc |grep
Load_Cycle_Count; sleep 120; done;
[root@localhost ~]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/VolGroup00-LogVol00
287G 34G 239G 13% /
/dev/hdc1 99M 28M 67M 30% /boot
tmpfs 506M 0 506M 0% /dev/shm
[root@localhost ~]#
I left it more than 120 seconds.
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