Corrupted USB drive partition table

hiddenocelot · 11-22-2021, 04:16 PM

Hi all,

I've had a USB that I'm trying to format but it seems to be giving me some trouble. Originally I had an ISO for a now unnecessary Linux distribution. I deleted this and formatted the drive but all is not well. It allows me to format ~20Gb out of 30Gb available into ext4, but no more. It seems ok in exFAT format for now but I'm not 100% sure if it works fine.

I am unable to shred the contents of the drive for some reason and it appears to have a corrupted partition table. I've used gdisk a little but this has not fixed anything. I don't need any of the data on the drive, although I intend to backup my system on it, so it's important that I can trust it.

The output from gdisk below highlights that the partition table is corrupted.

Code:

sudo gdisk /dev/sdb
GPT fdisk (gdisk) version 1.0.8

Caution: invalid backup GPT header, but valid main header; regenerating
backup header from main header.

Warning! Main and backup partition tables differ! Use the 'c' and 'e' options
on the recovery & transformation menu to examine the two tables.

Warning! One or more CRCs don't match. You should repair the disk!
Main header: OK
Backup header: ERROR
Main partition table: OK
Backup partition table: ERROR

Partition table scan:
  MBR: protective
  BSD: not present
  APM: not present
  GPT: damaged

****************************************************************************
Caution: Found protective or hybrid MBR and corrupt GPT. Using GPT, but disk
verification and recovery are STRONGLY recommended.
****************************************************************************

Command (? for help): v 

Caution: The CRC for the backup partition table is invalid. This table may
be corrupt. This program will automatically create a new backup partition
table when you save your partitions.

Identified 1 problems!

Does anyone know how to help? I was also unsure where to post this so I put it in general. I'm happy to get directed to somewhere more relevant

syg00 · 11-22-2021, 05:18 PM

Assuming a USB key/pen, why gpt ?.
It's almost mandatory on (big) disk these days, but not keys - it's needlessly complex for the job. I don't know why ext4 is limited like that, but it's not worth the effort to chase IMHO - try MBR.

hiddenocelot · 11-22-2021, 06:35 PM

Hmmm to be honest I don't know the difference, but I had the impression it was the more modern format. I'll try that out when I have the time

jefro · 11-22-2021, 06:50 PM

If you need data I think fdisk has a recovery mode option. Otherwise one can just clear it. Maybe some programs like gparted might call it initialize or something.

ondoho · 11-23-2021, 02:35 AM

AFAIU you do not need the data in the USB stick anymore?
And want to shred it before partitioning it anew?

I'd use dd for the shredding.
It's very simple, but you have to be 125% sure you have the right drive:

Code:

dd if=/dev/urandom of=/dev/sdX bs=4M

You need elevated privileges.
Replace X with your drive letter.
bs=4M is not necessary but will likely speed things up. Even so, it can take a while for 30GB.

Then, I'd use gparted to create a new partition table (MSDOS) and the partitions I want (all of them physical unless you plan to have more than 4).
And any ext4 partition can be larger than 20GB.