Comment 72 for bug 349767

On the machine where USB disc gets disconnected generally after two days
uptime, we have disabled the USB power management and this problem didn't
happen for cca 6 days uptime.

Following script has been added to the file /etc/rc.local

for i in /sys/bus/usb/devices/*/power/level; do echo on > $i; done

On following machines:
  10.0.3.57
  10.0.3.58
  10.0.3.40
  10.0.3.39

All these machines will be monitored, if usb disconnect problem occurs

This is the command for checking usb power management setting:
for i in /sys/bus/usb/devices/*/power/level; do echo $i; cat $i; done

auto - means that power management is enabled
on - means that usb will be always on (enabled)

We don't know why this helps.

Is there a kernel boot options to enable power level for all USB devices?

See also bug 701011.