HOWTO : Fix 'ALERT! : dev/XYZ does not exist' after upgrade to Dapper Drake

[Ted_Smith]

I will begin by saying that I am still new to Linux and learning myself every day. This HOWTO is the result of several failed installations attempts of Dapper (and upgrading to it from Breezy). I am documenting my experiences in the hope that someone else won't spend an entire week trying to fix the problems I had.

Scenario

You have Breezy Badger installed on your PC. You have an IDE disk connected to your IDE0 channel on the motherboard with, for arguments sake, a Windows partition and an Ubuntu partition on your disk. On your other IDE channel, IDE1, you have a CDROM\DVD Drive. You also have some other drives connected to an IDE adaptor (the number is insignificant but it could be several).

You decide to upgrade from Breezy Badger to Dapper Drake. You do the necessary upgrade steps, and everything seems to run without a hitch. You reboot. And your faced with a tragedy that looks something similar to the following :

 
Ubuntu Logo Here

Loading Essential Drivers :                 [OK]
Mounting Root File System :                blank
Waiting for root filesystem :              blank
 

It sits there for 3 or 4 minutes until eventually your faced with a black screen and a terminal shell with a message along the lines of

Begin: Waiting for root file system... ...
Cannot find /dev/hda2
ALERT : dev/hda2 does not exist

BusyBox Built In Shell
#_

If you're new to Linux, or just uneasy about what you're doing, this is without doubt an absolute show stopper!! And no, doing a fresh install (so wiping your earlier attempts and re-trying) will not get round the problem either. And no, installing from the CD won't help you either (trust me, it won't - been there, tried that, cried in my cup of English tea, and re-tried again!). It's a big fat mess (at least it seems to be). So what the cause, and how do you fix it? Read on.

The Cause

Ubuntu Dapper Drake (and I think it’s related to the 2.16 Kernel generally) re-assigns drive letter assignments very badly when your PC has multiple IDE devices installed. It was known as a bug prior to release but was only considered 'low priority'. Let me explain. You may have a disk set-up like this :

In Breezy Badger :
- hda 20Gb HDD
- hdc CD\DVD
- hde 160GB HDD
- hdf 160GB HDD

But on Dapper it becomes :
- hda 160GB HDD
- hdc 160Gb HDD
- hde 20Gb HDD
- hdf CD\DVD

So, your Breezy installation that was on hda get upgraded to Dapper, but after the upgrade something happens so that when you reboot Dapper thinks the root filesystem is on hda but 'hda' (the value 'hda' I mean) has been assigned to a different drive all together, But Dapper doesn’t know that.

OK. Well how the hell do I fix it?

1) Download the Dapper Install Live install CD and burn the ISO to CD : http://www.ubuntu.com/download

2) Test it works.

3) Using your current installation (not live CD) temporaily remove all the mount references to your additional drives from etc/fstab and copy them to a text file in your home folder (or better still an external storage medium) for use later on. Leave your standard root partition and the swap partition as they are.

Sudo gedit //etc/fstab

For example, change :

# /etc/fstab: static file system information.
#
# <file system> <mount point> 		  <type>  <options>       <dump>  <pass>
proc            /proc        		   proc    defaults        0       0
/dev/hde2       /           		   ext3    defaults,errors=remount-ro 0       1
/dev/hda5       none       		   swap    sw              0       0
/dev/hdd5	/home/ted/Mounts/ext3	   ext3    rw,user,auto	   0       0
/dev/hda1	/home/ted/Mounts/reiser    reiserfs  rw,user,auto  0       0 – Take these out
/dev/hdc        /media/cdrom0   udf,iso9660 user,noauto     0       0
/dev/hdd        /media/cdrom1   udf,iso9660 user,noauto     0       0
/dev/fd0        /media/floppy0  auto    rw,user,noauto  0       0

to :

# /etc/fstab: static file system information.
#
# <file system> <mount point> 		  <type>  <options>       <dump>  <pass>
proc            /proc        		   proc    defaults        0       0
/dev/hde2       /           		   ext3    defaults,errors=remount-ro 0       1
/dev/hda5       none       		   swap    sw              0       0
/dev/hdc        /media/cdrom0   udf,iso9660 user,noauto     0       0
/dev/hdd        /media/cdrom1   udf,iso9660 user,noauto     0       0
/dev/fd0        /media/floppy0  auto    rw,user,noauto  0       0

Save, and exit.

4) Install or upgrade your installation from Breezy to Dapper (this step is beyond the scope of this HOWTO).

5) Reboot. You will almost certainly find the problem will occur, but you never know, you might be OK in which case you don't need to read this . Otherwise, read on.

6) Turn off your PC and unplug the power to your additional drives leaving only the one with your operating system on plugged in (you must make sure this step is done accurately in light of your adjustments to fstab). In my example, this is the disk recognised as dev/hda2 in fstab.

7) Reboot using the live CD you downloaded and created earlier in step 1.

8) You should now be in the Live CD environment. Go to System, Administration, Disk Information, and look at how Dapper has assigned your single IDE drive and partitions. Most likely, it will be something like ‘/dev/hde2’ (instead of hda2). Make a note of that (in my case, hda2 had been changed to hde2).

9) Then you need to edit the boot loader of your main installation on your disk drive because it’s here where the confusion lies because entries are made that do not match what Dapper has assigns. To do that, we have to mount the partition with your main installation on with write access using the Live CD environment. So, while still in System Administration, Disk Information, navigate to your HDD with the install of Dapper on it, click the 'Partitions' tab and select the partition where it's actually installed. Then create a temporary mount point in the home folder of your Live CD session, and then click 'Enable'. You will see that if you then click Browse your main install files will be listed. See this Screenshot for an example.

10

sudo edit Your_Temporary_Mount_Point/boot/grub/menu.lst

Near the bottom, for each entry you should see lines relating to the various Linux Kernels you’ve had installed on your machine and the partitions that they reside. For example :

kernel /boot/vmlinuz-2.6.15-1-686 root=/dev/hda5 ro

where it says /dev/hda5 change it to the drive assignments that you noted earlier in step 8. For example,

kernel /boot/vmlinuz-2.6.15-1-686 root=/dev/hde5 ro

If you want, change all the other values for your Recovery Mode entries and earlier Kernel entries too because otherwise they won’t work later on when you need them. Alternatively, wait to see if it works at all first.

Save the file, and reboot.

11) With any luck, your new Ubuntu Dapper Drake system will now boot. Expect the usual graphics drivers problems especially if you’ve performed an upgrade (as opposed to fresh install) and if you used a specific driver for your graphics card such as Nvidia. Correcting that is another issue and beyond the scope of this HOWTO. It all depends on your graphics cards.

12) Shut-down, re-connect your additional drives, and reboot back into Ubuntu.

13) Go to System, Administration, Disk Information again and set new mount points for your additional drives. If you make them the same as before you can just copy and paste your mount entries that you removed earlier in step 3 back into fstab just as before except obviously you'll need to change the drive assignments in light of how Dapper has now decided to assign them. So whereas you may have had

/dev/hdd5	/home/ted/Mounts/ext3	   ext3    rw,user,auto	   0       0. look at how Dapper

Under Dapper it may now be

/dev/hde5	/home/ted/Mounts/ext3	   ext3    rw,user,auto	   0       0

I hope that helps.

PLEASE NOTE : It seems that every time your Linux kernal is upgraded, the re-assignment back to the wrong partitions occur so you have to edit the menu.lst file again using the Live CD environment. So keep this HOW TO in your favourites!!

Lastly, while this may seem infinately annoying at the time, it's no different to Windows assigning 'Drive C:' during installation to a drive other than what you intended when you have several disks present. On several occasions I've had to disconnect disks before re-installing a fresh copy of Windows for the very same reason. The only difference is that Windows copes with it whereas Linux doesn't like it. Like most things, this is why Windows is a bit messy whereas Linux is stricter and the by the book and rather than putting it up with it it wants you to fix it.

Other references : http://www.ubuntuforums.org/showthre...=186930&page=2

[oppio]

Hi,

I'm facing the problem addressed by this HOWTO after upgradind Dapper from kernel 2.6.15-23-386 to 2.6.15-25-386, together with other upgrades. I've tried everything but I still run into the problem without any solution.

The strange thing is that, after upgrading, my drives keep being mapped as they were before, but I get the "ALERT! /dev/hdb2 does not exist" message and get dropped to busybox.

Here comes my drives mapping:

- hda 40Gb HDD (windows)
- hdb 40Gb HDD (Fedora 4 on hdb1 and Kubuntu 6.06 on hdb2)
- hdc CD\DVD
- hdd 200GB HDD

I can say for sure that mappings didn't change because I checked at boot without the quiet and splash parameters.
My mobo has SATA controllers aswell but no drives plugged to.

I tried everything I could find in the forums but helplessly. I wonder why the hell can't it mount hdb2 if it finds it while booting ?!
And, how can I recover from this problem? I'd like avoiding reinstall from scratch.....


thanks in advance

[Mzee nyuki mpya]

Hi,

[Mzee nyuki mpya]

I'm not used to posting; this is my third time of typing this...

After 6 months of using Breezy, I found it easy to upgrade to Dapper, which I enjoyed for about 10 days. Then next time I tried to boot I had this problem!

When I tried the recovery option in Grub I got more information:

[4294674.903000] EXT3-fs error (device hdb1): ext3_check_descriptors: Inode bitmap for group 384 not in group (block 2147483647)!
[4294674.903000] EXT3-fs group descriptors corrupted!

I can now only use the PC with the Breezy Live CD. I can open System-Administration-Disks, but it doesn't allow me to enable access to it.
My plan is to have the Live CD in the DVD drive and a blank CD in the CD-RW drive and copy the files in my Home folder before wiping off Dapper and re-installing Breezy, as several people have suggested.
Does anyone know how to do this so I can avoid re-entering 6 months of Gnucash data?!

[Ted_Smith]

Oppio - have you done as I wrote in the HOW TO? You look to be having the same problem I had. If you follow the HOW TO, it should work.

Mzee - your problem looks like a seperate issue from the issue that this HOW TO addresses. I would suggest starting a fresh thread - I am sorry, I do not know enough to help you.

[MDesigner]

Nice post, but unfortunately doesn't apply to those of us who are not coming from a previous version of Ubuntu, or Linux at all. I'm doing a fresh install of Dapper Drake 6.06, and I'm getting this problem. Any ideas on how to resolve this? If I boot the live CD, /dev/sda3 is alive & well, and it is indeed the proper partition that I installed Ubuntu on (/dev/sda2 is swap). So why would it not work when booting on the HD?

[Halleck]

Nice post, but unfortunately doesn't apply to those of us who are not coming from a previous version of Ubuntu, or Linux at all. I'm doing a fresh install of Dapper Drake 6.06, and I'm getting this problem. Any ideas on how to resolve this?

Yes, information on what to do about a fresh install of Dapper would be greatly appreciated. I've been stuck for the past 12 hours or so trying to get my Ubuntu LiveCD and my Xubuntu alternate installation disc to work, but they continue to stall. My ubuntu cd freezes here:

Ubuntu Logo Here

Loading Essential Drivers :                 [OK]
Mounting Root File System :

Xubuntu prompts me for my language, location, and keyboard layout. After ostensibly detecting my CD-ROM drives, it freezes too.

If it's of any help, I'm installing this on my webserver, an old Pentium-II machine with 128mb of ram. That's why I thought xubuntu would be a good choice. It has two hard drives, a floppy drive, and two CD-ROM drives (the slave CD drive is actually a CD-RW.) Right now, Windows 98 is installed, but i'm running Mandrake 8.1 most of the time using lnx4win.

Wierd setup, I know.

BTW, I checked both discs on my desktop PC. They both passed their self-checks for defects and I was able to boot off the LiveCD successfully, so it's not an issue with the media.

Anyway, any help with this would be greatly appreciated. Thanks!

[MDesigner]

Halleck, do us a favor.. boot up ubuntu, but choose recovery mode. Watch the text fly by.. and when it hangs, just leave it for a while. I'm betting eventually you'll get an error that says "ALERT! /dev/whatever does not exist. Dropping to a shell."

[Halleck]

Halleck, do us a favor.. boot up ubuntu, but choose recovery mode. Watch the text fly by.. and when it hangs, just leave it for a while. I'm betting eventually you'll get an error that says "ALERT! /dev/whatever does not exist. Dropping to a shell."

Okay. My Ubuntu LiveCD does not have that option, but my Xubuntu CD does, so I tried that.

I left it for over half an hour, it's still hanging at the blue screen after the hardware detection.

[MDesigner]

Okay. My Ubuntu LiveCD does not have that option, but my Xubuntu CD does, so I tried that.

I left it for over half an hour, it's still hanging at the blue screen after the hardware detection.

OK, so much for that. I figured it's similar to the prob after installing Ubuntu. Sorry