newbie could use help. I have a toshiba satellite 2450 S203 512 Mb Ram, 40 Gb HDD, nvidea graphic card and usRobotics pcmcia(texas instrumental chipset = acx111 wifi). Win xp was preinstalled. I tried to install ubuntu 5.10.
The goal is to put as little as possible of the os on the HDD and a maximum on a usb external drive (seagate 160 Gb in a conceptronic case). BIOS does not let me boot from usb so putting all of the os on external drive is no option.

To keep the os print on the HDD as small as possible, during the install procedure I created (with the partitioning tool of the install procedure) a very small partition on hda ( 3 Gb) and mounted it as /boot. According to "Introduction to Linux, A hands on guide" from Machtelt Garrels this directory contains a kernel and startup files. I hoped this would suffice.

I placed the partition containing / on the external drive. Everything went fine and just before putting grub in the MBR of hda, my XP was recognized,thus saving grub was safe. Install finished off cleanly. BUT...

When I try to boot, Grub turns up, and then after a few seconds of loading the kernel I get an error message :
alert /dev/sda2 does not exist. then I find myself in shell level (?) and I'm blocked.

I've been reading the man pages on grub and the tutorials on external usb drives and usb cardreader (on this site) but couldn't find a clue on why sda is not up on booting.
Is what I'm trying to do possible at all ? If so, could someone point me to some newbie level documentation (or solutions) on the subject.

thanks for your time,

Grub has trouble with usb.
Try enabling usb legacy support in bios or try installing lilo.

will try it out. thx