Alert! /dev/sdax does not exist. dropping to a shell!

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Alert! /dev/sdax does not exist. dropping to a shell!

Postby bane on Sun Apr 19, 2009 6:05 pm

Hello,

I have looked over the current threads and noticed that people are having the same problem. Unfortunately, I can't get to the point of being able to attempt their suggested solutions. I'm pretty new to Linux/Unix so please bare with me here.. I'm trying to get comfortable enough to make the switch (from Windows). Here is my situation:

I recently installed Linux Mint 6 (Felicia) to a partition on my 360GB SATA drive, and after a successful install, I remove the Live CD, reboot and select the generic boot option. I can make it to the Usplash but before it finishes loading I get the output:

Gave up waiting for root device.
Missing modules (cat /proc/modules; ls /dev)
Alert! /dev/sda2 does not exist. dropping to a shell!

Now - I have read in a few threads that this can be fixed by modifying the fstab and menu.lst while running the Live CD. The problem is, I can't access any of these drives while running the Live CD. I get an error message "Unable to mount volume". I'm able to access some directories via the "Filesystem" icon while running the Live CD, but I'm assuming that it's a temporary file system... as there are no files/directories in the /media directory, which is where I would normally find /grub/grub-menu.lst.

This is how I setup my drive during the installation:
/dev/sda1 /windows ntfs (approx. 177Gb, primary)
/dev/sda2 / ext3 (approx. 10Gb, primary)
/dev/sda3 /home ext3 (approx. 170Gb, primary)
/dev/sda5 swap swap (approx. 2Gb, primary)

Like I said - I'm pretty new to Linux so please be gentle :) Let me know if you need more information.
Thanks!
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Re: Alert! /dev/sdax does not exist. dropping to a shell!

Postby 67GTA on Sun Apr 19, 2009 6:29 pm

First we need to see what your exact partitions are. Boot the live CD, open a terminal, and post the output of
Code: Select all
sudo fdisk -l
Once we get that info, we can use the live CD to mount your Mint partition, and have a look at some system files to see where the problem is.
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Re: Alert! /dev/sdax does not exist. dropping to a shell!

Postby bane on Sun Apr 19, 2009 6:46 pm

This is the output from running fdisk -l:

Code: Select all
Disk /dev/sda: 320.0 GB, 320072933376 bytes
255 heads, 63 sectors/track, 38913 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x01c30640

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *           1       23114   185663173+   7  HPFS/NTFS
/dev/sda2           23115       24359    10000462+  83  Linux
/dev/sda3           24360       38788   115900942+  83  Linux
/dev/sda4           38789       38913     1004062+  82  Linux swap / Solaris
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Re: Alert! /dev/sdax does not exist. dropping to a shell!

Postby 67GTA on Sun Apr 19, 2009 6:54 pm

From the live CD, open a terminal, and run
Code: Select all
sudo mount /dev/sda2 /mnt
This will mount your Mint root partition. You can access the system files by going to /mnt in the live CD file system. Then post a copy of /etc/fstab and /boot/grub/menu.lst from /dev/sda2.
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Re: Alert! /dev/sdax does not exist. dropping to a shell!

Postby bane on Sun Apr 19, 2009 7:02 pm

Here's the contents of /etc/fstab and /boot/grub/menu.lst, respectively.
Edit: I wasn't sure if you wanted the complete file contents or just the entries relevant to sda2. I can re-post the entire contents of both files if you don't mind scrolling.

Code: Select all
# /etc/fstab: static file system information.
#
# <file system> <mount point>   <type>  <options>       <dump>  <pass>
proc            /proc           proc    defaults        0       0
# /dev/sda2
UUID=06f2d0ca-4320-482b-88e8-44be0a09991b /               ext3    relatime,errors=remount-ro 0       1


Code: Select all
title      Linux Mint 6, kernel 2.6.27-7-generic
root      (hd0,1)
kernel      /boot/vmlinuz-2.6.27-7-generic root=/dev/sda2 ro quiet splash
initrd      /boot/initrd.img-2.6.27-7-generic
quiet
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Re: Alert! /dev/sdax does not exist. dropping to a shell!

Postby 67GTA on Sun Apr 19, 2009 7:29 pm

Is that all of your fstab file? Can you post all of it, and all of the menu entries in grub?
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Re: Alert! /dev/sdax does not exist. dropping to a shell!

Postby bane on Sun Apr 19, 2009 7:34 pm

Absolutely. Sorry about that. Here are the complete file contents:

/etc/fstab
Code: Select all
# /etc/fstab: static file system information.
#
# <file system> <mount point>   <type>  <options>       <dump>  <pass>
proc            /proc           proc    defaults        0       0
# /dev/sda2
UUID=06f2d0ca-4320-482b-88e8-44be0a09991b /               ext3    relatime,errors=remount-ro 0       1
# /dev/sda3
UUID=0a355f7a-69b4-42b2-b4c2-94de83c6dc1d /home           ext3    relatime        0       2
# /dev/sda1
UUID=DEF8F888F8F86067 /windows        ntfs    defaults,umask=007,gid=46 0       1
# /dev/sda4
UUID=6cf046e0-fcc9-4350-be04-65048e38ab68 none            swap    sw              0       0
/dev/scd0       /media/cdrom0   udf,iso9660 user,noauto,exec,utf8 0       0


/boot/grub/menu.lst
Code: Select all
# menu.lst - See: grub(8), info grub, update-grub(8)
#            grub-install(8), grub-floppy(8),
#            grub-md5-crypt, /usr/share/doc/grub
#            and /usr/share/doc/grub-legacy-doc/.

## default num
# Set the default entry to the entry number NUM. Numbering starts from 0, and
# the entry number 0 is the default if the command is not used.
#
# You can specify 'saved' instead of a number. In this case, the default entry
# is the entry saved with the command 'savedefault'.
# WARNING: If you are using dmraid do not change this entry to 'saved' or your
# array will desync and will not let you boot your system.
default      0

## Graphical boot menu location
gfxmenu=/boot/gfxmenu/default.message

## timeout sec
# Set a timeout, in SEC seconds, before automatically booting the default entry
# (normally the first entry defined).
timeout      10

# Pretty colours
color cyan/blue white/blue

## password ['--md5'] passwd
# If used in the first section of a menu file, disable all interactive editing
# control (menu entry editor and command-line)  and entries protected by the
# command 'lock'
# e.g. password topsecret
#      password --md5 $1$gLhU0/$aW78kHK1QfV3P2b2znUoe/
# password topsecret

#
# examples
#
# title      Windows 95/98/NT/2000
# root      (hd0,0)
# makeactive
# chainloader   +1
#
# title      Linux
# root      (hd0,1)
# kernel   /vmlinuz root=/dev/hda2 ro
#

#
# Put static boot stanzas before and/or after AUTOMAGIC KERNEL LIST

### BEGIN AUTOMAGIC KERNELS LIST
## lines between the AUTOMAGIC KERNELS LIST markers will be modified
## by the debian update-grub script except for the default options below

## DO NOT UNCOMMENT THEM, Just edit them to your needs

## ## Start Default Options ##
## default kernel options
## default kernel options for automagic boot options
## If you want special options for specific kernels use kopt_x_y_z
## where x.y.z is kernel version. Minor versions can be omitted.
## e.g. kopt=root=/dev/hda1 ro
##      kopt_2_6_8=root=/dev/hdc1 ro
##      kopt_2_6_8_2_686=root=/dev/hdc2 ro
# kopt=root=/dev/sda2 ro

## default grub root device
## e.g. groot=(hd0,0)
# groot=(hd0,1)

## should update-grub create alternative automagic boot options
## e.g. alternative=true
##      alternative=false
# alternative=true

## should update-grub lock alternative automagic boot options
## e.g. lockalternative=true
##      lockalternative=false
# lockalternative=false

## additional options to use with the default boot option, but not with the
## alternatives
## e.g. defoptions=vga=791 resume=/dev/hda5
# defoptions=quiet splash

## should update-grub lock old automagic boot options
## e.g. lockold=false
##      lockold=true
# lockold=false

## Xen hypervisor options to use with the default Xen boot option
# xenhopt=

## Xen Linux kernel options to use with the default Xen boot option
# xenkopt=console=tty0

## altoption boot targets option
## multiple altoptions lines are allowed
## e.g. altoptions=(extra menu suffix) extra boot options
##      altoptions=(single-user) single
# altoptions=(recovery mode) single

## controls how many kernels should be put into the menu.lst
## only counts the first occurence of a kernel, not the
## alternative kernel options
## e.g. howmany=all
##      howmany=7
# howmany=all

## should update-grub create memtest86 boot option
## e.g. memtest86=true
##      memtest86=false
# memtest86=true

## should update-grub adjust the value of the default booted system
## can be true or false
# updatedefaultentry=false

## should update-grub add savedefault to the default options
## can be true or false
# savedefault=false

## ## End Default Options ##

title      Linux Mint 6, kernel 2.6.27-7-generic
root      (hd0,1)
kernel      /boot/vmlinuz-2.6.27-7-generic root=/dev/sda2 ro quiet splash
initrd      /boot/initrd.img-2.6.27-7-generic
quiet

title      Linux Mint 6, kernel 2.6.27-7-generic (recovery mode)
root      (hd0,1)
kernel      /boot/vmlinuz-2.6.27-7-generic root=/dev/sda2 ro single
initrd      /boot/initrd.img-2.6.27-7-generic

title      Linux Mint 6, kernel Last successful boot
root      (hd0,1)
kernel      /boot/last-good-boot/vmlinuz root=/dev/sda2 ro quiet splash  last-good-boot
quiet

title      Linux Mint 6, memtest86+
root      (hd0,1)
kernel      /boot/memtest86+.bin
quiet

### END DEBIAN AUTOMAGIC KERNELS LIST

# This is a divider, added to separate the menu items below from the Debian
# ones.
title      Other operating systems:
root


# This entry automatically added by the Debian installer for a non-linux OS
# on /dev/sda1
title      Windows XP Media Center Edition
root      (hd0,0)
savedefault
makeactive
chainloader   +1
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Re: Alert! /dev/sdax does not exist. dropping to a shell!

Postby 67GTA on Sun Apr 19, 2009 7:51 pm

That all looks normal. Post the output from a terminal for
Code: Select all
sudo blkid
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Re: Alert! /dev/sdax does not exist. dropping to a shell!

Postby bane on Sun Apr 19, 2009 7:53 pm

>blkid
Code: Select all
/dev/sda1: UUID="DEF8F888F8F86067" TYPE="ntfs"
/dev/sda2: UUID="06f2d0ca-4320-482b-88e8-44be0a09991b" TYPE="ext3"
/dev/sda3: UUID="0a355f7a-69b4-42b2-b4c2-94de83c6dc1d" SEC_TYPE="ext2" TYPE="ext3"
/dev/sda4: UUID="6cf046e0-fcc9-4350-be04-65048e38ab68" TYPE="swap"
/dev/loop0: TYPE="squashfs"
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Re: Alert! /dev/sdax does not exist. dropping to a shell!

Postby 67GTA on Sun Apr 19, 2009 8:44 pm

I can't figure out why it can't find your root partition. When the grub menu comes up, hit "e" to edit. Then select the kernel line(second line down) and hit "e" again. Then at the end of the line add this:
Code: Select all
root=UUID=06f2d0ca-4320-482b-88e8-44be0a09991b


Before:
Code: Select all
/boot/vmlinuz-2.6.27-7-generic root=/dev/sda2 ro quiet splash


After:
Code: Select all
/boot/vmlinuz-2.6.27-7-generic root=UUID=06f2d0ca-4320-482b-88e8-44be0a09991b ro quiet splash


Then hit "enter" and then "b" to boot. If that works, you can edit /boot/grub/menu.lst to include the UUID intsead of /dev/sda2
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Re: Alert! /dev/sdax does not exist. dropping to a shell!

Postby bane on Sun Apr 19, 2009 9:44 pm

I tried booting with
Code: Select all
/boot/vmlinuz-2.6.27-7-generic root=UUID=06f2d0ca-4320-482b-88e8-44be0a09991b ro quiet splash


and the last line of the error now reads "Alert! /dev/disk/by-uuid/06f2d0ca-4320-482b-88e8-44be0a09991b does not exist. dropping to a shell!". After that error there is a (initramfs) prompt.. which quickly outputs this:
Code: Select all
[41.016026] ata1.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x6 frozen
[41.016078] ata1.00 cmd a0/01:00:60:00/00:00:00:00:00/a0 tag 0 dma 96 in
[41.016079] cdb 12 00 00 00 60 00 00 00 00 00 00 00 00 00 00 00
[41.016081] res 40/00:02:00:24:00/00:00:00:00:00/a0 Emask 0x4 (timeout)
[41.016220] ata1.00: status { DRDY }


I've tried using labels(as another thread suggested) and that doesn't seem to work. Not sure what the problem could be.

Thanks for all of your help - very much appreciated!
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Re: Alert! /dev/sdax does not exist. dropping to a shell!

Postby bane on Mon Apr 20, 2009 1:40 pm

I managed to get it to successfully boot twice now. I added "all_generic_ide" to the boot option and it went through the same process, outputting few errors but eventually loaded the UI after about 3-5 minutes. I'm not exactly sure why it worked.. due to my drive being SATA. Oh well, it boots now (knock on wood).

For the sake of possibly helping others, I changed the kernel line in menu.lst to look like this:
Code: Select all
/boot/vmlinuz-2.6.27-7-generic root=/dev/sda2 ro quiet splash all_generic_ide


That being said - it will only boot with the "all_generic_ide" option every other boot attempt. So, I'm going to try booting with the UUID again to see if that clears up the problem.
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Re: Alert! /dev/sdax does not exist. dropping to a shell!

Postby 67GTA on Mon Apr 20, 2009 3:58 pm

It sounds like your having trouble with your sata drive if that command worked. What is in /boot/grub/device.map?
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Re: Alert! /dev/sdax does not exist. dropping to a shell!

Postby bane on Mon Apr 20, 2009 5:00 pm

This is my /boot/grub/device.map. Due to the problems that I've been having, I decided to add the partition lines but didn't notice a difference.
Code: Select all
(hd0)   /dev/sda
(hd0,0)   /dev/sda1
(hd0,1)   /dev/sda2
(hd0,2)   /dev/sda3
(hd0,3)   /dev/sda4
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Re: Alert! /dev/sdax does not exist. dropping to a shell!

Postby 67GTA on Mon Apr 20, 2009 5:26 pm

Everything looks fine. It must be something to do with your sata drive, and the drivers being loaded. I saw a similar thread on the Ubuntu forums, and it was completely random. Sometimes it would boot, sometimes it wouldn't no matter what was tried. I'm at a loss. One last thing to look at is /dev/disk/by-uuid and make sure the UUID numbers there match up with what is in fstab.
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Re: Alert! /dev/sdax does not exist. dropping to a shell!

Postby bane on Mon Apr 20, 2009 5:42 pm

Everything matches up. I'm confused as to why this is working. I will keep digging through the forums to see if anyone has gotten any closer to a solution. Thanks again for all of your help!
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Re: Alert! /dev/sdax does not exist. dropping to a shell!

Postby idiotkiwi on Mon Apr 20, 2009 9:50 pm

I have been following this discussion as I have a case of UUID incompatibilities which shows up with differences between the results shown by blkid and fstab. The incompatibility is not causing me any problems but which is the correct result.??

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Re: Alert! /dev/sdax does not exist. dropping to a shell!

Postby 67GTA on Tue Apr 21, 2009 2:51 pm

The blkid results are the ones to trust. Blkid reads the current UUID of each device. Post a copy of fstab and the output of
Code: Select all
sudo fdisk -l
and
Code: Select all
sudo blkid
.
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Re: Alert! /dev/sdax does not exist. dropping to a shell!

Postby confusion on Wed Jun 10, 2009 2:09 am

Hello, I recently installed (20 minutes ago) Linux Mint Community Edition 5 with KDE and had the same problem. On first boot after a successful installation it would drop to a shell with the message Alert! /dev/hda1 does not exist. I found this post trying to google for assistance with the matter. I tried a reinstall with the same results, but noticed that it listed my devices right before it timed out. sda1, sda2,sda3(root,home and swap). So I rebooted again and changed the root device from root=/dev/hda1 to root=/dev/sda1, and now I am up and running without a problem. So my suggestion is that while you think it may have installed to and labeled a device one way, it may be completely different, so perhaps you should try to point it at a different partition and see what the results are. It worked for me. Also, this is a temporary change. You have to do this every time you restart your computer unless you edit your menu.lst, located in /boot/grub/menu.lst, I believe. Hope this helps.
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