btrfs-find-root - Linux

Overview

btrfs-find-root is a command-line tool used to search a given block device or file for the root filesystem of a Btrfs filesystem. It is primarily useful for identifying the correct device or file where a Btrfs filesystem is located, making it crucial for system rescue and recovery scenarios.

Syntax

btrfs-find-root [options] [device|file]

Options/Flags

  • -B, –block-size BYTES: Specify the block size to use, in bytes. Defaults to 4096.
  • -m, –metadata-offset BYTES: Specify the metadata offset to use, in bytes. Defaults to 64.
  • -s, –search-size BYTES: Specify the maximum size of the search area, in bytes. Defaults to the size of the device or file.
  • -v, –verbose: Print additional information during the search.
  • -h, –help: Print usage information.

Examples

Basic Usage

To search for the root filesystem on a block device (/dev/sda):

btrfs-find-root /dev/sda

Searching a Specific Range

To search a specific range of bytes on a file (myfile.img):

btrfs-find-root -s 10000000 myfile.img

Modifying Metadata Offset

To specify a custom metadata offset:

btrfs-find-root -m 128 /dev/sdc1

Common Issues

  • Device Not Recognized: Ensure that the specified device or file exists and is accessible.
  • No Root Filesystem Found: The device or file may not contain a Btrfs filesystem or the root filesystem may have been damaged.
  • Unexpected Output: The output may contain multiple matches if the device or file contains multiple root filesystems.

Integration

btrfs-find-root can be used in conjunction with other tools for system recovery:

  • fdisk -l: To obtain a list of block devices and their partitions.
  • ddrescue: To recover data from a damaged device.
  • btrfs-restore: To restore a backup of the root filesystem.

Related Commands

  • btrfs-check: Checks the integrity of a Btrfs filesystem.
  • btrfs-rescue: Provides various rescue and recovery options for Btrfs filesystems.
  • dumpe2fs: Dumps the superblock and other metadata from an ext2/ext3/ext4 filesystem.