Ubuntu
mdadm package

Removing a software package that causes Ubuntu to fail booting

Asked by Andrew Long

Hi,

My NAS failed recently, two discs were mirrored RAID 1 so I put them into my workstation to see what could be salvaged.
Both discs checked out OK, Ubuntu recognised the RAID but wouldn't build it (not enough components for array).

I found a number of recommendations that involved installing mdadm.
Installed that, no errors, but it didn't make any difference to accessing the RAID
Rebooted to see if that helped with the new package and the PC now fails boot. It does list the O/S disc during boot, there are no visible errors, but the login screen never appears

I'd like to get it to boot to see what went wrong!
So now I have no NAS and my main pc is also buggered!

I can boot from an Ubuntu 10. CD and mount the O/S HD fine.
I'm going to dig in the start up files and see if I can find anything suspect, but I I have very limited experience with Ubuntu so any advice would be welcome!

As a last resort what is the best way to back up the whole disc, bearing in mind I am running from the CD O/S not the "real" O/S so I expect some access problems? At least then I can start again and reinstall from scratch :(

Cheers,

   Andy

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actionparsnip (andrew-woodhead666) said : 		#1

http://www.omgubuntu.co.uk/2011/09/live-usb-sticking-grub-2-video/

Will get the OS booted...

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Andrew Long (y2j03w) said : 		#2

Thanks, very informative. I
Sorry for the delay, have tried those instructions again and again to no avail :(

I get no errors following theinstructions, everything seems to work, but the machine still won't boot from the HD. It will boot fine from the USB drive.

The machine runs through the BIOS, lists the HD info, says AHCI BIOS installed, then the screen goes to "cannot display this video mode" (as it always has done), only after a moment it used to show the Ubuntu graphics screen, now it just stays Cannot display... :(

Once booted from the USB can see and mount the old OS disc. It reports as healthy, bootable and partitioning "master boot record".

Any more clues?

  Andy

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delance (olivier-delance) said : 		#3

Can you have the boot menu ? (If you have only Ubuntu installed, you will need to press <Shift> at start)

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Andrew Long (y2j03w) said : 		#4

No, I don't get a menu.

Only ubuntu is installed on this machine. Pressing <shift> gives the message "GRUB loading ." after the BIOS info and immediately before the screen goes to "cannot display this video mode"

It's a Dell PC with a Dell flat panel monitor (not a CRT). Does GRUB display errors or menus in some resolution not supported by a standard Dell screen?

The UNetbootin menu display when booting from USB as per the instructions above, so whatever video mode that works OK.

(sorry for the delay - been away for the weekend without even a 'phone signal!)

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delance (olivier-delance) said : 		#5

Please provide data about boot configuration

There is a standard script provided to analyze boot configuration. Could you download script at:
   http://sourceforge.net/projects/bootinfoscript/
Then in a terminal (Ctrl+Alt+T) run command:
    sudo bash [path/to/the/download_folder]/boot_info_script.sh
This will produce a file named: RESULTS.txt. Paste content of this file in http://paste.ubuntu.com/ and provide in this thread the link to Web page. Please don't post file directly in thread, else it will make thread difficult to read.

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Andrew Long (y2j03w) said : 		#6

It won't boot at all from the original O/S hard drive so I can't run any script.
If I run the script after booting from USB or a different HD will it give results of any use?

After booting from USB and CHROOT I tried to remove the mdadmin package, but that didn't help.
I also got another hard drive, installed ubuntu 11 on that, installed the mdadmin package and it did the same again! :(
Maybe it's trying to use the non raid O/S disc on sda as part of an array by default?

This h/d I don't care about and can wipe / reinstall at will, however I would like to get the old HD back to retrieve my email archive and then I still have the original issue of accessing the RAID discs!

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actionparsnip (andrew-woodhead666) said : 		#7

You can boot to the liveCD and chroot, the commands you run will affect the installed OS.

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delance (olivier-delance) said : 		#8

If I run the script after booting from USB or a different HD will it give results of any use? Yes!

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Andrew Long (y2j03w) said : 		#9

OK booted from USB chroot to / and ran the script.
Pasted at paste.ubuntu.com/834618/

So dev/sda is the drive it won't boot from
Sdb and sdc are the RAID discs out of the broken NAS and sdd is the USB drive, that all makes sense to me so far!

   Andy

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