Grub2, Asus and external hard drive, unknown filesystem

Question

linux

The problem was observed by me twice - on Asus EEEPC 700 and 900 laptops. Grub, installed on the internal disk of the laptop, does not see the partitions of the external hard disk. Diagnosed by typing "root (hd" into the console and pressing Tab. The hard disk itself is rude, it also determines the number of partitions correctly, but it writes on each unknown filesystem, it refuses to see files, it also loads the system. I tried both ext2 / 3/4, and fat, and even ntfs, then I realized that the problem is not in the file system, but in the rough or bios.At the same time, the booted system sees the hard disk perfectly.Attention, the question is: how to boot the system installed on an external drive? disk?

Answer 1

How is the external drive connected? Rough what version?