How to Use the Command 'btrfs restore' (with Examples)
The btrfs restore command is a potent utility designed to assist users in recovering files from a damaged Btrfs (B-tree File System) filesystem. Primarily aimed at salvaging vital data from corrupted storage devices, it allows files to be selectively restored based on specific criteria. Given the complexities involved in managing Btrfs filesystems, this command can be crucial for system administrators and users attempting to recover from data loss incidents.
Use Case 1: Restore All Files from a Btrfs Filesystem to a Given Directory
Code:
sudo btrfs restore path/to/btrfs_device path/to/target_directory
Motivation: The need to restore all files from a damaged Btrfs filesystem can arise from scenarios where a complete backup is required, without risking further damage to the original storage device. This command helps users retrieve all globally important files and directories for archiving or analysis, ensuring minimal data loss.
Explanation:
sudo: Runs the command with administrative privileges, which is necessary for accessing and modifying filesystem contents.btrfs restore: The command used to begin the recovery process.path/to/btrfs_device: Specifies the path of the Btrfs filesystem device from which files are being restored.path/to/target_directory: Indicates the directory where the restored files will be placed.
Example Output:
Restoring file: /example/document.txt
Restoring file: /example/photo.jpg
Operation completed successfully. All files restored to /path/to/target_directory.
Use Case 2: List (Don’t Write) Files to be Restored from a Btrfs Filesystem
Code:
sudo btrfs restore --dry-run path/to/btrfs_device path/to/target_directory
Motivation: Before undertaking a full restoration, users might want to understand which files are recoverable. This use case is beneficial for evaluating data integrity and deciding whether a full restoration process is worth commencing. It acts as a preliminary step in the recovery protocol.
Explanation:
--dry-run: An option that allows users to simulate the restoration process without making any changes, listing potential files for recovery.path/to/btrfs_device: Designates the source Btrfs filesystem.path/to/target_directory: A required parameter, even though files will not actually be restored.
Example Output:
Listing file: /example/document.txt
Listing file: /example/photo.jpg
Dry run complete. 2 files listed for potential restoration.
Use Case 3: Restore Files Matching a Given Regex to be Restored from a Btrfs Filesystem
Code:
sudo btrfs restore --path-regex regex -c path/to/btrfs_device path/to/target_directory
Motivation: Sometimes users only need to recover specific files, such as those matching certain naming patterns. This approach is especially useful in large datasets where only certain file types or names are of interest. It saves time and reduces resource consumption by focusing only on the necessary files.
Explanation:
--path-regex regex: Uses a regular expression to filter files, specifying which files and directories to target for restoration.-c: Ensures that the match is case-insensitive, making the regex more flexible.path/to/btrfs_device: Identifies which Btrfs device to process.path/to/target_directory: Defines where matched files will be restored.
Example Output:
Restoring file: /example/image.PNG
Restoring file: /example/Image.TIFF
Operation completed successfully. Matched files restored to /path/to/target_directory.
Use Case 4: Restore Files from a Btrfs Filesystem Using a Specific Root Tree bytenr
Code:
sudo btrfs restore -t bytenr path/to/btrfs_device path/to/target_directory
Motivation: When a filesystem’s integrity is questioned, users might want to explore different versions or snapshots for restoration. This use case allows restoration from a specific root tree, offering a way to backtrack to a particular filesystem state and recover files from there.
Explanation:
-t bytenr: Specifies the byte number of the root tree to be used for restoration, which effectively allows reverting to a particular file system snapshot.path/to/btrfs_device: Is the damaged Btrfs filesystem.path/to/target_directory: Target path for restored content.
Example Output:
Restoring file from root tree 256: /example/archive.zip
Specific root tree restoration successful.
Use Case 5: Restore Files from a Btrfs Filesystem with Metadata, Extended Attributes, and Symlinks, Overwriting Files in Target
Code:
sudo btrfs restore --metadata --xattr --symlinks --overwrite path/to/btrfs_device path/to/target_directory
Motivation: For users requiring an exact replication of files, including all properties like metadata, extended attributes, and symlinks, this advanced restoration is invaluable. It comes in handy when files in the target directory might already exist and need to be replaced completely.
Explanation:
--metadata: Ensures metadata associated with files is also restored.--xattr: Restores extended file attributes, which can include numerous metadata items like permissions or user-defined attributes.--symlinks: Recovers symbolic links, preserving the integrity and functionality of the file system references.--overwrite: Allows existing files in the target directory to be replaced with restored versions.path/to/btrfs_device: The source device for restoration.path/to/target_directory: Destination for enriched file recovery.
Example Output:
Restoring file: /example/myapp.conf with metadata and xattr
Symlink restored: /example/config_link
Operation completed with full resource recovery. Files and links reestablished in /path/to/target_directory.
Conclusion
The btrfs restore command is a versatile and powerful tool for data recovery from a Btrfs filesystem. Whether the goal is to list available files, restore selectively, or recover all data with complex properties, this command offers a wide array of options to meet the various needs of users during data recovery operations. Selecting the appropriate use case based on your specific scenario can make recovering data a streamlined process, minimizing downtime and data loss.
