Hard disks only spin down for a few seconds

[Sockmonster]

Hi, I'm running fedora on a laptop and have installed Laptop-Mode-Tools. When I enter laptop mode my hard disks spin-down but almost immediately start up again. When I run "hdparm -Y /dev/sda" the drive spins-down for approx 5 sec.

I've set dirty_writeback_centisecs to 5000 and have set vm.swappiness to 100 to try and limit the amount of disk writes, but it is having no effect. It seems that something is constantly writing to my disk!!

Any help would be grand

Thanks.

[flansuse]

What value is -B (power management) set to with laptop-mode? I've had issues with anything lower than 128. Too many parks of the head is not good for the drive in the long term.

[Sockmonster]

Not sure what -B is, how do i check?
Thanks.

[flansuse]

Originally Posted by Sockmonster

Not sure what -B is, how do i check?
Thanks.

With the hdparm tool, you can manually set certain hard drive attributes, such as power management with the -B option. In the configuration file for laptop-mode, there is a section that sets the -B level based on three conditions: is laptop-mode running on battery? on AC? is it disabled?

This file is located under /etc/laptop-mode/laptop-mode.conf

BATT_HD_POWERMGMT
LM_AC_HD_POWERMGMT
NOLM_AC_HD_POWERMGMT

These values specify the power management level for your hard drives. The legal values for these options can be found in the hdparm manual page, in the documentation of the -B option

You will see the current values it is set to. Most likely the NOLM value is 254, and the value for laptop-mode being active is either 1 or 128. Leave the 254 alone, but change the other values to 128 or greater. If you would rather your drive not constantly spin down and start up, over and over, set it to 254.

You can also manually check the current power management level of any drive with hdparm.

The following command displays the drive's information, while only revealing the lines with the word "power" in them:

hdparm -I /dev/sda | grep -i power

[flyingfsck]

Howdy,

You have to stop the syslog daemon if you want the hard disk to spin down.

[stevea]

Originally Posted by flyingfsck

Howdy,

You have to stop the syslog daemon if you want the hard disk to spin down.

Well - you need get /var/log and maybe /tmp OFF the hard disk. Try mounting a tmpfs for these (F15 does this automatically IIRC).

I haven't tried in a few months but the kflush daemon at that time ignored the dirty_writeback_centisecs.
Setting vm.swappiness to 100 isn't a good value and is only effective IF you ae swapping - and generally you shouldn't be on an end-user system.