[SOLVED] Booting minimal image from USB stick

AchilleTalon · Last edited by AchilleTalon on Sun Jul 26, 2015 4:01 am; edited 1 time in total

Hi everyone,

I am trying to boot the minimal image in order to install Gentoo Linux on a laptop. I am running into a very strange problem I have never seen before and I really don't know what I can do to fix this problem.

First of all, the laptop is having a Windows 7 image which no longer boot neither. Second, it had a previous Gentoo Linux "version" installed and instead of trying to upgrade it, I decided to reinstall it because it is outdated for a long time.

So, I decided to modify the partitions of my only drive, I then booted with the USB stick and used fdisk to erase the swap partition in order to reduce its size and create a new partition in between.

After I did that, I was no longer able to boot sanely from the USB stick. WTF is going on? The first sign something went wrong is the udev events processing takes almost infinite time. I can interrupt it to proceed further, but when I finally get the prompt after a very long booting process I can use the keyboard only few seconds before it freezes. After waiting for a long time, I can see finally some characters I typed appearing on the display, then it is active for few more seconds, etc. The gpm process is started, but the mouse doesn't seem to work at all even if no error message was issued during the boot process.

I am desesperated to find what is going on.

Any ideas? Hints?

I can trying to boot normally without the usb stick, but the boot process get interrupted (looks like a kernel panic even if I cannot seen the kernel panic message), but this can be somewhat normal since the swap partition number has changed. That's why I need to boot on the usb stick to at least correct my /etc/fstab.

But, why everything seems to freeze?

I managed to issue the fdisk /dev/sda command, with many minutes delay between each small time window I can type something. So, here is what I get just after doing this, the welcome message is displayed followed by a message in red saying:

Keruskerfuerst · Posted: Mon Jul 13, 2015 6:21 am Post subject:

Do you have a second computer?
Try to update the Bios of the not working computer.

Maybe the hardware of the not working computer is defective.
HDDfirmwarevirus?

NeddySeagoon · Posted: Mon Jul 13, 2015 9:05 am Post subject:

AchilleTalon,

Something is broken. I suspect its fdisk.
Try a clean install of System Rescue CD on your USB stick. Its Gentoo based, so you will feel quite at home.

Its unlikely to be failed hardware - there are too many checks along the way before the hardware boots.
The logical partitions in an MSDOS partition table are stored in a linked list. If you were to get loops in the list,
the list output would never end.

Do you need to salvage any data from /dev/sda5 and later ?
If so, post the first two loops ot the partition table starting at /dev/sda5. We can mount the partitons without using the partition table.
_________________
Regards,

NeddySeagoon

Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail.

AchilleTalon · Posted: Tue Jul 14, 2015 3:09 am Post subject:

@NeddySeagoon,

I finally managed to get the partition table as shown by the fdisk command and yes, I need to salvage some data from partitions in the extended partition. I agree with you it is unlikely to be a hardware problem. I believe the problem is actually I am getting a loop in the linked list, the command stop at partition 60. When booting with the USB stick with the minimal distro it scans /dev/sda0 to /dev/sda255 before switching to /dev/sdb1 (the USB stick drive). This number of 256 is looking like a limit once reached to give up indicating in fact the loop is infinite.

Here is the output of the fdisk -l /dev/sda command:

NeddySeagoon · Posted: Tue Jul 14, 2015 8:51 am Post subject:

AchilleTalon,

Heres the analysis ...

AchilleTalon · Posted: Tue Jul 14, 2015 1:17 pm Post subject:

NeddySeagoon,

there is not partition after sda10. From sda11 it is a repeating pattern of partitions sda6 to sda10. Yes, the gap of unallocated blocks is expected since I didn't reallocated all the blocks after deleting the partition. The only partition I really care about is the Linux LVM partition where I have data I would like to salvage if possible. sda10 is a new empty unformatted partition.

As soon as I have extra time I will run the required test.
_________________
Achille Talon Hop!

NeddySeagoon · Posted: Tue Jul 14, 2015 2:07 pm Post subject:

AchilleTalon,

At face value, sda8 and sda9 overlap by one block.

AchilleTalon · Posted: Tue Jul 21, 2015 11:55 pm Post subject:

Just an update. I cannot boot with a USB stick or even a USB drive without being trapped into a never ending process. I guess it has something to do with the linked-list loop for the disk partitions.

What kind of boot media and what stuff on it will make my laptop to boot? Do I have to disable something about the drive to avoid the boot process trying to figure out everything on that disk?
_________________
Achille Talon Hop!

NeddySeagoon · Posted: Wed Jul 22, 2015 7:42 pm Post subject:

AchilleTalon,

How did you boot to get to fdisk?
If that works so should other forms of booting.

As long as that was Linux, it will do to attempt to recover your data.
_________________
Regards,

NeddySeagoon

Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail.

AchilleTalon · Posted: Thu Jul 23, 2015 12:03 am Post subject:

I booted with my USB external hard drive. However, it was a very only kernel version. So, I decided to update it to get the latest version of the tools and since that time I run into this problem, almost the same with the USB stick which is having as well a recent image.
_________________
Achille Talon Hop!

NeddySeagoon · Posted: Thu Jul 23, 2015 4:32 pm Post subject:

AchilleTalon,

That you were able to boot at all shows its not a problem with your broken partition table.

Try with System Rescue CD on a usb stick. Follow the instructions to install it onto the stick.
_________________
Regards,

NeddySeagoon

Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail.

AchilleTalon · Posted: Sat Jul 25, 2015 6:06 pm Post subject:

I finally got it and here is the output from the analysis from testdisk:

NeddySeagoon · Posted: Sat Jul 25, 2015 7:47 pm Post subject:

AchilleTalon,

The simple way forward is to wipe everything, make a new partition table and reinstall from backups.

If you feel lucky you can delete all of your logical partitions (5 and on) then recreate them with the exact same starting and ending values as they have now.
That way, your data will be preserved in place. Because of the on disk data layout, after the first logical partition, (sda5) you have to get this right first time.

If you feel really adventureous, you can fix the loop in the linked list with a hex editor.
_________________
Regards,

NeddySeagoon

Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail.

AchilleTalon · Posted: Sat Jul 25, 2015 8:39 pm Post subject:

I feel a bit adventurous. I mean, I am curious how I could fix the linked-list. Do you have more information, a URL to a wiki, website or something to help me understand and get started? I may not walk down this road, I will see.
_________________
Achille Talon Hop!

AchilleTalon · Posted: Sun Jul 26, 2015 4:00 am Post subject:

BTW, after doing the testdisk scan, suffice to write the partition table to restore everything in a working state. I still have to recreate my second Linux /boot and shrink my swap space to do so, however, the partition table is now in a sane state. I will avoid using fdisk next time and rely on parted instead.
_________________
Achille Talon Hop!

NeddySeagoon · Posted: Sun Jul 26, 2015 9:19 am Post subject:

AchilleTalon,

If you are happy there are no false positives, you can let testdisk rewrite the partiton table for you.
If it gets partitions 1..4 wrong, there is no harm done.
If it gets partition 5 wrong there will be no damage to the data in partition 5 until it writes the entry for partition 6, whick will be written at the end of the incorrect partition 5 entry.
This may be anywhere on disk.

Be sure that the partition table testdisk wants to write is a truncated version of your posts here.
_________________
Regards,

NeddySeagoon

Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail.

AchilleTalon · Posted: Sun Jul 26, 2015 1:54 pm Post subject:

NeddySeagoon,

since nothing has been written to the disk after the partitions were created and testdisk discovered the partitions before the change, writing this partition table fixed the problem.

I am still curious about using an hex editor to edit the partition table. Maybe another time I will explore this with a disk I have no fear to lost anything on it.

Thanks for you help, very much appreciated.
_________________
Achille Talon Hop!