Fix Corrupted USB Drive in Linux: Step-by-Step Repair Guide

Understanding the Problem and Preparing for Repair

Corrupted USB drives can be a significant issue, especially when they contain important data. Fortunately, Linux offers a variety of tools and methods to help repair and recover data from these drives.

Backing Up Your Data

Before attempting any repairs, it is crucial to back up your data to prevent further loss. Here’s how you can create a compressed full backup image of your USB drive using Linux:

Connect and Locate Your USB Drive:
- Connect your USB drive to your computer.
- Open a terminal and locate your USB drive using:
```
ls /dev/disk/by-id
```
  Note down the device identifier (e.g., /dev/disk/by-id/YOUR_FLASH_DRIVE).
Create a Backup Image:
- Use the dd command along with gzip to create a compressed backup image:
```
sudo dd if=/dev/disk/by-id/YOUR_FLASH_DRIVE status=progress | gzip -c > /home/USERNAME/backups/BACKUP_NAME.img.gz
```
  This command will create a compressed image file of your USB drive.
Restore the Backup:

To restore the backup, use the following command:

sudo gzip -cd /home/USERNAME/backups/BACKUP_NAME.img.gz | sudo dd of=/dev/disk/by-id/YOUR_FLASH_DRIVE status=progress

This will restore the backup image to your USB drive.

Fixing Corrupted Filesystem with FSCK

If your USB drive has a corrupted filesystem, you can use the fsck command to repair it.

Unmount the USB Drive:
- Ensure the USB drive is unmounted before running fsck.
Run FSCK:
- Use the fsck command to check and repair the filesystem:
```
sudo fsck -y /dev/disk/by-id/YOUR_FLASH_DRIVE-part1
```
  Replace YOUR_FLASH_DRIVE-part1 with the actual partition identifier of your USB drive.

Using GUI Tools for Repair

For those who prefer a graphical interface, the "Disks" tool in Ubuntu can be very helpful.

Launch Disks:
- Open your apps menu and search for “disks.” Launch the app when you locate it.
Select Your USB Drive:
- Choose your USB drive from the list on the left.
Repair Filesystem:

Click on the icon with the two cogs and select “Repair Filesystem” to follow the wizard and fix the filesystem.

Format the USB Drive:
- If the filesystem is beyond repair, you can format the USB drive:
  - Click on the icon with the two cogs again and choose “Format Partition.”
  - Enter a name for your USB drive, select a filesystem (e.g., Ext4, NTFS, FAT), and decide whether to perform a quick or full format.

Command-Line Methods for Advanced Repair

Sometimes, GUI tools may not be sufficient, and you need to use command-line tools for a more detailed repair.

Delete Partitions with FDisk:
- Plug in your USB drive and run dmesg to note the device name (e.g., /dev/sdb):
```
sudo dmesg
```
- Run fdisk to delete and recreate partitions:
```
sudo fdisk /dev/sdb
```
  Type p to list partitions, d to delete them, n to create a new primary partition, t to set the partition type (e.g., c for FAT32), and w to write the changes.
Format the Partition:
- Format the new partition using mkfs.vfat:
```
sudo mkfs.vfat -n USBDISK /dev/sdb1
```
  This will create a FAT32 filesystem on the partition.
Wipe and Reformat with DD:

If the drive is severely corrupted, you can wipe it with zeros and then format it:
```
sudo dd if=/dev/zero of=/dev/sdb bs=4096 status=progress
```
Follow this by formatting the drive using mkfs:
```
sudo mkfs.vfat -n USBDISK /dev/sdb1
```
This method ensures a complete wipe and reformat of the drive.

Troubleshooting Common Issues

Drive Not Detected:
If your USB drive is not detected, try using dmesg and ls /dev to confirm the device name. Sometimes, the drive might be recognized but not mounted properly.
Input/Output Errors:
If you encounter input/output errors during backup or repair, it may indicate a hardware issue. In such cases, using ddrescue might help recover data, but the drive may be beyond repair.
Frozen Terminal:

If commands like mkfs or fsck freeze, it could be due to a faulty drive. Running dd with status updates can help diagnose the issue:

while true; do sudo kill -USR1 $(pgrep dd); sleep 5; done

This will provide periodic status updates on the dd command.

Conclusion

Repairing a corrupted USB drive in Linux involves a combination of backing up data, using filesystem repair tools, and sometimes resorting to low-level formatting. By following these steps, you can often recover your data and restore your USB drive to a usable state. However, if the drive is physically damaged, it may be irreparable, and replacing it might be the best option.