On 01/01/21 14:40, John Edwards wrote:
Hi
On Fri, Jan 01, 2021 at 01:01:11AM +0000, Mark Preston via GLLUG wrote:
I was trying to create a bootable persistent Linux Mint 20 USB stick with
EFI support from a linux mint20 .iso downloaded from the internet. but
something went wrong and...now I get an unallocated hard drive message.
I would like to know how to repair / fix an unallocated hard drive, if
possible, preferably without losing the data on it.
Most obvious question would be "do you have backups"?
I will assume for the moment the answer is "no".
<snip>
Disk /dev/sda: 1.8 TiB, 2000398934016 bytes, 3907029168 sectors
Disk model: ST2000DX001-1CM1
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disklabel type: gpt
Disk identifier: 855C35AB-DF58-4AD0-A242-58BC6E6BD581
Looks like something has deleted the GPT partition tables on your 2TB
hard drive.
<snip>
knoppix@Microknoppix:~$ fsck -y /dev/sda
<snip>
You should not run fsck on a drive device ("sda") but instead run it
on the partition that holds the filesystem, but in this case you can't
because the partition information has been removed from the drive.
You need to get that partiton layout information back before doing any
more work on the drive. If you have backups that contain information
about the partitions on that drive (eg a hardware report from
something like 'lshw') then you can us that.
Otherwise you will need to use a hard drive utility to scan the whole
hard drive looking for possible partitions and filesystems, and then
choose whichever layout seems to look right to you.
The main tool I have used for this in the past is 'testdisk', which is
available as a Debian and Ubuntu package (and can be installed if you
boot from a Live Debian or Ubuntu CD/DVD) and might already be on that
Knoppix DVD. There might be better tools developed more recently.
If you have no backups and have a spare 2TB drive then you may want to
consider making a complete copy of the whole disk (using something
like 'dd' or 'clonezilla') and run 'testdisk' on the new drive so that
you don't damage any data on the original.
Lastly it might worth thinking about how the partition table got
removed. This could be a fault with the hard drive (unlikely because
there should be 2 GPT partition tables, but run a full SMART test as
soon as possible to be safe) or it might be that the wrong device was
choosen when you tried to create the bootable USB stick.
On 01/01/21 16:14, Chris Bell via GLLUG wrote:
Hello Mark
Knoppix appears to show sda as a 2TB disk partitioned using GPT which will
install a GPT partition immediately after the space normally used by the DOS
MBR to provide more space for information about multiple main partitions, not
just the maximum of 4 physical partitions in the old MS-DOS. Most computers
search for the MBR, so it is used to re-direct the BIOS to the GPT partition.
The main boot sequence is then controlled from the GPT partition, and none of
the other partitions will be labelled as bootable.
I often see some unallocated space at either end of the disc space, usually
less than 1 sector, but most of sda appears to be a single partition, possibly
using a swap file instead of a swap partition.
Perhaps the disc was re-partitioned as a GPT disc, which would overwrite the
original MS-DOS system, but then just left not further partitioned or
formatted.
There appears to be more information about sdb and its partitions without
mention of corruption.
If sda is corrupted do not try to alter it. There was a package "photorec"
designed to recover deleted photos which was later enhanced to recover almost
anything and may be re-named "testdisk". It is not a quick and easy recovery,
but can examine, list, recover, and copy as many directories and files as
possible to another formatted disc.
Hi John and Chris,
Thank you for your further replies. They are helping me to develop a
recovery plan.
I have a full backup of the home directory from the end of October which
I expect will contain nearly all the files I need. I installed the HMRC
Paye Basic Tools system and this is one of my concerns, but it won't be
the end of the world. This is a 32 bit program for Linux, but I got it
working on this 64 bit machine which I was quite pleased about. Whether
I can repeat that trick I'm not sure. I think you're right that the
Linux Mint 20 install removed the partitions, but I never installed this
on the hard drive, so hopefully most of the previous files are still
there somewhere. The computer never had any Windows operating system
installed as far as know. It's about time I got a new PC. I think I'll
change the hard drive and put Linux Mint 20 on the new drive and copy
the existing 2TB disk using GNU ddrescue to an external hard drive
before removing it and the copy for further analysis with programs like
testdisk. Maybe eventually it can be repartitioned and rebooted
successfully.
--
Regards,
Mark
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