TimeCapsule external drive sleeping

Hi

my config is as follows:

- ATV 1st generation with firecore's atv enhancement including XBMC 11
- movie files are stored on an usb drive (WD essential 2TB) which is connected to my time capsules usb port
- mac clients (online/switched on only temporary)

XBMC is running perfectly, I can watch videos from the usb drive.

Only one problem: My macs are not necessarily online or even switched on.
When I start my ATV and run XBMC without accessing the usb drive in advance, I cannot access the movies in my database (error: file not found)

All works well when I access the usb drive from one of my macs before starting xbmc
So it seems that the drive is sleeping and is not waked up by xvmc

Is there a way to send a kind of "ping" to the drive when starting xbmc or when trying to access a movie?
I like to use ATV and XMBC
- without doing a manual wakeup of the usb drive
- without being forced to start my mac client to access the drive
- without being forced to have a mac running to do a cron job that wakes up the usb drive (or keep it awake)

Any clue?

Regards