Why Copy GPT Partition Tables?

When configuring RAID or setting up identical disks, it’s essential to have the same partition tables across all disks. While sfdisk worked well for MBR (msdos) partition tables, it does not support GPT. Fortunately, we can achieve this using sgdisk.

Prerequisites and Safety Checks

Backup Your Data

🔴 WARNING: Always backup important data before manipulating partition tables!

bash
# Create a backup of the partition table
sudo sgdisk --backup=disk1_backup.gpt /dev/sd_src

# Optional: Create full disk image
sudo dd if=/dev/sd_src of=disk1_full_backup.img bs=4M status=progress

Verify Disk Identification

bash
# List all disks with their identifiers
lsblk -o NAME,SIZE,MODEL,SERIAL

# Show detailed disk information
sudo fdisk -l

Install gdisk

Install gdisk based on your distribution:

Ubuntu/Debian:

bash
sudo apt-get install -y gdisk

RHEL/CentOS/Fedora:

bash
sudo dnf install -y gdisk

Arch Linux:

bash
sudo pacman -S gptfdisk

Copy GPT Partition Table

Basic Copy Operation

bash
# Copy partition table
sudo sgdisk -R /dev/sd_dest /dev/sd_src

# Verify the operation succeeded
echo $?

Advanced Copy Options

bash
# Copy with progress information
sudo sgdisk --display-alignment -R /dev/sd_dest /dev/sd_src

# Copy and preserve original UUIDs (use with caution)
sudo sgdisk --backup=original.gpt /dev/sd_src
sudo sgdisk --load-backup=original.gpt /dev/sd_dest

Explanation:

  • -R /dev/sd_dest /dev/sd_src → Copies the partition table from source disk to destination disk
  • --display-alignment → Shows alignment information during copy
  • --backup → Creates a backup of the partition table
  • --load-backup → Restores a partition table from backup

Update UUIDs for Unique Identification

Randomize UUIDs

bash
# Generate new UUIDs
sudo sgdisk -G /dev/sd_dest

# Verify unique UUIDs
sudo blkid /dev/sd_src*
sudo blkid /dev/sd_dest*

Why is this necessary?

  • Prevents duplicate partition detection
  • Avoids boot failures and system confusion
  • Essential for RAID and multi-disk setups
  • Prevents mount conflicts in fstab

Verification Steps

Check Partition Table

bash
# Compare partition tables
sudo sgdisk -p /dev/sd_src
sudo sgdisk -p /dev/sd_dest

# Verify alignment
sudo sgdisk --verify /dev/sd_dest

Validate Partitions

bash
# List all partitions
sudo fdisk -l /dev/sd_dest

# Check partition details
sudo parted /dev/sd_dest print

Troubleshooting

Common Issues and Solutions

  1. Disk Busy Error

    bash
    # Unmount all partitions
sudo umount /dev/sd_dest*

# Stop any RAID arrays
sudo mdadm --stop /dev/md*

  2. Invalid GPT Error

    bash
    # Fix GPT errors
sudo sgdisk --verify /dev/sd_dest
sudo sgdisk --rebuild-gpt /dev/sd_dest

  3. UUID Conflicts

    bash
    # Force UUID regeneration
sudo sgdisk --randomize-guids /dev/sd_dest

Real-World Examples

Setting up Software RAID

bash
# Copy partition table to all RAID disks
for disk in /dev/sd[b-e]; do
    sudo sgdisk -R $disk /dev/sda
    sudo sgdisk -G $disk
done

Preparing for Disk Migration

bash
# Copy and preserve alignment
sudo sgdisk --display-alignment -R /dev/newdisk /dev/olddisk
sudo sgdisk -G /dev/newdisk

Recovery Procedures

Restore from Backup

bash
# Restore partition table from backup
sudo sgdisk --load-backup=disk1_backup.gpt /dev/sd_dest

# Verify restoration
sudo sgdisk -p /dev/sd_dest

Emergency Recovery

bash
# Attempt to recover damaged GPT
sudo sgdisk --rebuild-gpt /dev/sd_dest

# Create new protective MBR
sudo sgdisk --gpttombr /dev/sd_dest

Conclusion

Using sgdisk, you can reliably clone GPT partition tables between disks, ensuring consistency in RAID setups and disk cloning operations. This method provides robust support for modern GPT-based partitions with built-in safety features and verification options.

Best Practices

  1. Always backup before partition operations
  2. Verify disk identifiers carefully
  3. Check UUIDs after copying
  4. Test mount points after completion
  5. Keep backup files until verification is complete