Solaris

@hicksd:
hmmm, I could actually plug it in another machine and install something there. Also, maybe I could connect it to another Linux machine (if I can find one). If the Linux machine could see it, then that would also mean it is a Solaris (driver) problem, right?

@DukeNuke:
The longest duration the drive was connected was aprox. 2h.

The thing is that the lamp is blinking and it is turned on when I plug it in, but after some time it turns off. When I give some command that does something with devices, the light goes "on" again. Could that mean it is a power problem and that I would need a exHDD with external power source?

My reasoning behind suggesting booting a Debian LIVE DVD on that machine was to check the hardware, the HP and the ext-HDD can communicate and that you don't have a hardware issue.

While I'm here on this thread, let me just say that what you are experiencing is classic for failing to stop volume services (volfs). Generally, to format such a USB device this service must be stopped and it won't talk to you until you do. Need to double check.

We tried on another server and it became visible when the volfs service was disabled. I tried that on my HP server but to no awail... Because of that, we are now using different external HDD - 2 TB, USB 2.0, with external power source.

Thank you all for your help.