How to set up system with boot partition on USB (pendrive)?

Note: I am doing such setup for the first time so I don’t know if there is a problem with given opensuse version or problem with what I am doing.

System: openSUSE 11.4 RC1

Desired setup: entire system except /boot partition on hard disk, /boot partition on USB (pendrive). Aim – making impossible to boot from hard disk, forcing boot from the USB (please, don’t question my aim, I am just trivializing the issue here to shorten the description).

Setup: I set /home and / partitions on hard disk (/sda), /boot partition on USB (/sdb), I selected the options to “Boot From Boot Partition” as well as “Boot From Master Boot Record”. Finally I selected “Boot Loader Options” and selected “Set active flag in Partition Table for Boot Partition”. I installed the system.

What works:
a) without pendrive inserted I cannot start the system
b) with pendrive inserted GRUB menu shows up and system is ready to boot

**The problem: **after initial starting, there is long pause, and system switches to text mode with error:

drive "/dev/disk/by-id/id_of_my_pendrive" is not found

Since the console worked, I logged in, and yes, actually there was not such disk found. But the disk (pendrive) was there – the initial booting took place not from void, but from it. So why it is not present?

Out of curiosity, I pulled it out, and plugged it in back, now it was visible in “dev/disk/…”.

**Question: **what should I change/tweak for correct booting the system from pendrive? Or is a bug in 11.4 installer? I would like to setup everything as it should be done – I mean within installer.

What I found so far:
Booting encrypted system from USB stick - Gentoo Linux Wiki

it is similar problem to mine, but only similar. I have other symptoms.

Thank you in advance for your help.

UPDATE: It might be a bug actually. See:

The simple problem is that you cannot boot from the pendrive in Linux until the system has read fstab. You can only place the /boot partition on a disk that can be reached by an instruction from the MBR.

What you are trying to do will not protect your system from someone inserting a Live-CD in a CD/DVD drive.

One possibility, AFAIK, is to boot directly from the pendrive by entering the BIOS setup and changing the order in which devices are polled. However, unless you have set up some other means to protect the hard disk from access from a Live CD, you may simply have more hassle without any benefit.

Thank you for your reply.

I am marking this as SOLVED because since I am able to set up system as I wished with LXDE (without sweat) and I am unable to do the same with Gnome, there has to be something with dependency module of them, or with installer.

I will post a explanation here, as I get one.