The situation: When I suspend the computer in Ubuntu, which is installed on an external hardrive connected through USB, it does not wake up properly.

Now, of course, this may be due to the USB hardware... it's most likely because the hardware is reset, as would be the soundcard and other things...

But I think it has worked before.

Is there any way to get around this problem, or should I just forget about suspending the computer? Or maby change the suspend settings in the BIOS?

External drives go through a detection-throws-event process when the kernel
is awake enough to notice the USB device. Since your kernel is on the external drive
it might be hard to wake up ...

I don't know the details, but there are ways to tell your kernel that some USB device is always present. That might help your situation. Of course it might also mean that you must always use the same USB socket on your workstation.

This is an interesting problem. Likely it applies to all USB-connected drives
including flash. There are lots of flash-based live distros now.

Let us know whatever you learn.
~~~ 0;-Dan

Your external harddrive get its power from USB connector, right? Is the USB connector powered on when the computer is suspended?

Follow-up: Sometimes it is a CMOS setting to enable USB-power even though the workstation or laptop is power-down. Sometimes there are special port hardware.
My laptop has many USB ports, but one has yellow internals (not the standard black) and is power-on even with the laptop power-off. That said, I had to find the CMOS setting and enable this feature. It was disabled by default.


~~~ 0;-Dan

Sorry for the delay.

From a couple of tests, I find that all USB ports seem to stay powered-on after suspend.
When the computer is on, they output 5.3V, while in suspend, they output 4.5V.
I believe this is negligeble -- there seems to be no problem here.

However, now I've got deal with the kernel, which may be a problem.

I should also try another live distro from a USB drive and see if it works.

As far as I'm concerned, it works if I change the suspend mode to low power mode in the CMOS settings,
instead of the ram-save one...

Using the original mode, links to an external harddrive connected to by usb are disrupted.
No explanation, but using an alternate mode works.

Note: Loading from a USB drive worked in the original mode.