System Administration Guide: Devices and File Systems


The superblock stores much of the information about the file system, which includes the following:

Because the superblock contains critical data, multiple superblocks are made when the file system is created.

A summary information block is kept within the superblock. The summary information block is not replicated, but is grouped with the primary superblock, usually in cylinder group 0. The summary block records changes that take place as the file system is used. In addition, the summary block lists the number of inodes, directories, fragments, and storage blocks within the file system.