The file /usr/share/doc/linux-doc/usb/persist.txt.gz mentions that the USB-persist capability can be enabled for a given USB device by writing 1 to the file persist in that device's directory in /sys/bus/usb/devices/$device/power. This is said — if I understood correctly — to allow mountings of volumes on the drive to persist across power loss during suspend.

However, I've discovered that the device I'd like to enable this facility for — a USB hard drive — does not have such a file in its corresponding directory, and that attempts to create it are rebuffed.

Is there perhaps a kernel module that needs to be loaded for this to work? Do I need to build a custom kernel? I'm running ubuntu 10.10.