Unstable boot for Ubuntu Karmic i386 installed in external USB harddisk

[Lawrence Tsang]

Hi All,

     I am a newbie in Grub 2 using the Ubuntu Karmic i386 system installed in an external harddisk. My computer has two internal harddisks and one external USB harddisk. The USB disk contains two partitions, the 1st one is for data and the 2nd one is installed with Ubuntu Karmic i386. 

     At system bootup, when I force the BIOS to boot from the external disk, the Grub 2 menu appears and I choose the 1st entry to boot my Ubuntu Karmic. The Karmic system sometimes boots normally into a fully functional system with no apparent error. However, at certain times, the Karmic boots into a "initramfs" prompt with the following messages :

Gave up waiting for root device
.....
.....
ALERT ! /dev/sdc2 does not exist. Dropping to a shell !
.....
(initramfs)

     After examining the "grub.cfg" file, I find the corresponding bootup menuentry to be :

### BEGIN /etc/grub.d/10_linux ###
menuentry "Ubuntu, Linux 2.6.31-19-generic" {
        recordfail=1
        if [ -n ${have_grubenv} ]; then save_env recordfail; fi
        set quiet=1
        linux   /boot/vmlinuz-2.6.31-19-generic root=/dev/sdc2 ro   quiet splash
        initrd  /boot/initrd.img-2.6.31-19-generic
}

     In the "linux" line of the menuentry, it has been set that "root=/dev/sdc2". I think this may be the cause of the unstable boot problem. 

     In the "initramfs" prompt, I don't see any /dev/sdc2 (using "ls /dev/sd*"). I could only see /dev/sdg1 and /dev/sdg2. Perhaps the linux kernel sometimes recognizes my Ubuntu Karmic partition as /dev/sdc2 and sometimes as /dev/sdg2. 

     How could I set the Grub 2 menuentry for a stable boot? Any idea?

     Thanks for any suggestion.

Regards
Lawrence