Mount Btrfs raid 5 from failed ReadyNas 104 on Linux - aka how I restore data from my ReadyNas

2 min read 25-10-2024

the ifix

Mount Btrfs raid 5 from failed ReadyNas 104 on Linux - aka how I restore data from my ReadyNas

If you're facing data loss due to a failed ReadyNAS 104, don't panic! In this article, we'll guide you through the process of mounting a Btrfs RAID 5 file system on Linux to restore your valuable data. This comprehensive step-by-step guide is designed to be clear and easy to follow.

Understanding the Problem

Your ReadyNAS 104 has encountered a failure, and you need to access the data stored in its Btrfs RAID 5 configuration. The original scenario looks like this:

# Example code for understanding purposes
sudo mount /dev/sdX /mnt/mydata

In this code snippet, sdX refers to the device containing your RAID 5 array, and /mnt/mydata is the mount point where you want to access your data. However, simply using this command won’t work due to the complexity of Btrfs RAID configurations.

Step-by-Step Guide to Restore Your Data

Identify the Drives: First, you'll need to identify the drives that were part of your RAID 5 array. Use the following command to list your disks:
```
lsblk
```
Look for your RAID devices, which should be labeled as sdX where X is a letter representing the drive.
Install Btrfs Tools: Ensure that you have the necessary tools to work with Btrfs. If you haven't done so, install the Btrfs utilities using the package manager:
```
sudo apt-get install btrfs-progs
```
Create a Mount Point: Create a directory where you'll mount the RAID array:
```
sudo mkdir /mnt/mydata
```
Mount the RAID: Use the following command to mount the Btrfs RAID array. Replace sdX with the specific device names of your RAID members.
```
sudo mount -o recovery /dev/sdX /mnt/mydata
```
If the RAID 5 has degraded due to a failed drive, you can try the following command which allows for mounting even when not all drives are present:
```
sudo mount -o degraded /dev/sd[abcd] /mnt/mydata
```
Here, sd[abcd] represents all the available disks in your RAID setup.
Access Your Data: Once the RAID is mounted successfully, you can navigate to /mnt/mydata and access your data as needed:
```
cd /mnt/mydata
ls
```
Backup Your Data: It is crucial to back up your data once you've successfully accessed it. Copy the files to another device to prevent future loss.

Additional Considerations

Understanding RAID 5: RAID 5 offers redundancy through striping with parity, meaning your data is distributed across multiple drives. This configuration can withstand the loss of one drive. However, you should always have a backup strategy.
Filesystem Health: If you're experiencing issues, you can check the health of the Btrfs filesystem by running:
```
sudo btrfs check /dev/sdX
```
Repairing Btrfs: If your filesystem is damaged, you can attempt to repair it. Note: This step can be risky, so ensure you have backups before proceeding.
```
sudo btrfs check --repair /dev/sdX
```

Conclusion

Restoring data from a failed ReadyNAS 104 using Btrfs RAID 5 on Linux can be a daunting task, but with the right tools and techniques, you can retrieve your important files. Always remember to maintain a solid backup plan moving forward to prevent similar issues in the future.

Useful Resources

This guide aims to equip you with the knowledge and steps necessary to recover your data successfully. Happy restoring!