Linux Showing Wrong Hard Drive Sizes After Failed dd Clone (BTRFS RAID1)

Background

BTRFS is a modern copy-on-write filesystem for Linux, providing multiple features such as snapshots, checksums, and RAID-like functionality. RAID1, in particular, is used to mirror data across two or more devices for redundancy.

Problem Description

When attempting to clone a BTRFS filesystem using the command btrfs fi clone /dev/sdX /dev/sdY, the following error occurs:

Error creating clone source and destination have the same device id

This error occurs even when the source and destination drives have different sizes. The issue is further complicated when trying to set up a RAID1 array with different drive sizes.

Solution

The solution is to create a new BTRFS filesystem on the destination drive, then copy the data from the source drive to the destination drive using the btrfs send and btrfs receive commands. Here's an example:

# Create a new BTRFS filesystem on the destination drive
sudo mkfs.btrfs /dev/sdY

# Mount the source and destination drives
sudo mount /dev/sdX /mnt/source
sudo mount /dev/sdY /mnt/destination

# Send the data from the source drive to the destination drive
sudo btrfs send /mnt/source | sudo btrfs receive /mnt/destination

# Create a RAID1 array on the destination drive
sudo btrfs balance start -dconvert=raid1 -mconvert=raid1 /mnt/destination

# Unmount the drives
sudo umount /mnt/source
sudo umount /mnt/destination

When cloning a BTRFS filesystem or setting up a RAID1 array with different drive sizes, it's important to use the btrfs send and btrfs receive commands instead of the btrfs fi clone command. This will ensure that the data is copied correctly and that the RAID1 array is set up properly.

References

• BTRFS Wiki: https://btrfs.wiki.kernel.org/index.php/Main_Page
• BTRFS Man Page: https://man7.org/linux/man-pages/man8/btrfs.8.html
• BTRFS Send/Receive Example: https://btrfs.wiki.kernel.org/index.php/Using_Send_and_Receive

Note: This article is for informational purposes only. The author is not responsible for any damage or data loss that may occur as a result of following the instructions provided.