"gave up waiting for root device" while booting

[ChaosChris2009]

I installed Ubuntu 10.10 inside Windows 7 today, Ubuntu 10.10 finished installing and all just fine

but when I try to boot into Ubuntu 10.10 from the boot menu I get this error

"gave up waiting for root device" while booting

and it mentions something about BusyBox

Help?

[lukeaw]

Same deal here, I freshly installed UNR 10.10 on my Lenovo S10-2 writing over Ubuntu 10.04, alongside Windows 7. The full message is:

Gave up waiting for root device. Common problems:
 - Boot args (cat /prov/cmdline)
   - Check rootdelay= (did the system wait long enough?)
   - Check root= (did the system wait for the right device?)
 - Missing modules (cat /proc/modules; ls /dev)
ALERT!  /dev/sdb7 does not exist.  Dropping to a shell!


BusyBox v1.15.3 (Ubuntu 1:1.15.3-1ubuntu5) built-in shell (ash)
Enter 'help' for a list of built-in commands.

(initramfs)

I was a bit wary during install because I created a logical partition ~200MB ext2 for /boot to sit on, followed by a ~70GB btrfs partition for /, then ~3GB for swap space.
If I remember correctly these were /dev/sdb6 /dev/sdb7 and /dev/sdb5 respectively, so the alert in the message seems to refer to my swap space (though I will check this) - Edit: corrected; /boot / and swap are 6, 7 and 5, but are actually on /dev/sda

[lukeaw]

Update: I installed from a USB flash drive, which I assume was assigned /dev/sda during installation. However, now I've completed the installation and removed the flash drive my main hard disk is /dev/sda, which is why I was getting the above boot error. I've edited grub's config from the shell as follows and it's got me a step further:

$ mkdir -p /mnt/boot
$ mount /dev/sda6 /mnt/boot
$ grep -F /dev/sdb7 /mnt/boot/grub/*
/mnt/boot/grub/grub.cfg:        linux   /vmlinuz-2.6.35-22-generic root=/dev/sdb7 ro   quiet splash
/mnt/boot/grub/grub.cfg:        linux   /vmlinuz-2.6.35-22-generic root=/dev/sdb7 ro single
$ sed -i -e 's#/dev/sdb#/dev/sda#g' /mnt/boot/grub/grub.cfg
$ reboot

I'm now staring at the more friendly graphical boot screen but not quite at the desktop yet; "The disk drive for /boot is not ready yet or not present", "Continue to wait; or Press S to skip mounting or M for manual recovery"

[lukeaw]

Final update: I'm sure the gurus out there were shouting the answer out loud at their screens

I figured /boot wasn't being found so pressed M which dropped me to a shell. I corrected the fstab with the same sed command.

$ sed -i -e 's#/dev/sdb#/dev/sda#g' /etc/fstab
$ reboot

...And I'm now playing with the shiny new Unity interface!

@Chris: I hope you're able to get something out of my posts here, shout if you need anything clarifying. To summarise: find and mount your partition containing grub, see where it's looking for your root filesystem. If it's not correct you've found your problem

[ABitTooSpicy]

lukeaw, I am getting the same exact error except mine says "ALERT! /dev/sda1 does not exist. Dropping to a shell!"

Could you walk me through the fix? (pretend you are talking to a 5 year old!)

[wildmanne39]

lukeaw, I am getting the same exact error except mine says "ALERT! /dev/sda1 does not exist. Dropping to a shell!"

Could you walk me through the fix? (pretend you are talking to a 5 year old!)

Hi, did you install ubuntu with wubi like the orginal poster did? if so have a look at this link.
http://ubuntuforums.org/showthread.php?t=1639198

[lukeaw]

lukeaw, I am getting the same exact error except mine says "ALERT! /dev/sda1 does not exist. Dropping to a shell!"

Could you walk me through the fix? (pretend you are talking to a 5 year old!)

How did you install Ubuntu - from the live CD or from a USB flash drive?

On a possibly related note I've noticed that even with 11.04 if you have an ISO image stored on a flash drive and boot from that, the installer still offers to unmount it before proceeding