Linux: Find Alternative Superblocks

In Linux, a superblock is a data structure that contains information about the file system, such as the file system type, the size of the file system, and the location of the root directory.

To find alternative superblocks in Linux, you can use the "mke2fs" command with the "-n" option. The "-n" option allows you to search for alternative superblocks on the file system.

For example, to search for alternative superblocks on the file system mounted at "/dev/sda1", you can use the following command:

mke2fs -n /dev/sda1

This will scan the file system and display any alternative superblocks it finds.

For example, the output might look like this:

mke2fs 1.45.5 (07-Jan-2020)
Found a valid secondary superblock at block 32
Found a valid secondary superblock at block 8193
Found a valid secondary superblock at block 16385
Found a valid secondary superblock at block 24577
Found a valid secondary superblock at block 32769
Found a valid secondary superblock at block 40961
Found a valid secondary superblock at block 49153

This shows the location of the alternative superblocks on the file system.

You can then use one of these alternative superblocks to try to recover the file system if the primary superblock is damaged or corrupted. To do this, you can use the "e2fsck" command with the "-b" option followed by the block number of the alternative superblock.

For example, to use the alternative superblock at block 8193 to check the file system, you can use the following command:

e2fsck -b 8193 /dev/sda1

This will use the alternative superblock at block 8193 to check the file system and try to repair any problems it finds.

Note: The steps above are just a few examples of how you can find and use alternative superblocks in Linux. The specific steps you need to take may vary depending on your system and the configuration of the file system.