XFS inode, directory and superblock

In the context of the XFS filesystem, please explain the following terms:

  • inode
  • directory
  • superblock

In the context of the XFS file system, the following terms have specific meanings:

  1. Inode: An "inode," short for "index node," is a fundamental data structure within the XFS file system. It serves as a metadata container that stores essential information about a single file or directory. This metadata includes details such as the file's size, ownership, permissions, timestamps (creation, modification, access), and pointers to the data blocks on disk that hold the actual content of the file. In essence, the inode acts as a reference point that enables the file system to locate and manage the associated data blocks efficiently.

  2. Directory: A "directory" is a specialized type of file in the XFS file system that serves as a container for storing names and corresponding inodes of other files and subdirectories. Directories allow for the organization and hierarchical structuring of files within a file system. They provide the means to navigate and access files through a logical and user-friendly structure. Directories also have their own inodes that store metadata about the directory itself, including its size, ownership, permissions, and the inodes of the contained entries.

  3. Superblock: The "superblock" is a critical data structure in the XFS file system that holds essential information about the entire file system. It acts as a master control block that stores vital parameters and statistics about the file system's layout, configuration, and usage. This information includes details about the size of data and metadata blocks, the total number of inodes, the location of the root directory, the block size, and more. The superblock serves as a starting point for the file system and is consulted during the mount process to ensure proper initialization and functioning of the file system.

In summary, within the XFS file system:

  • "Inodes" store metadata about individual files and directories, facilitating efficient data block management.
  • "Directories" are special files used to organize and manage the hierarchy of files and subdirectories.
  • The "Superblock" contains critical information about the overall file system's configuration and layout, aiding in its proper initialization and functioning.

This article was updated on September 1, 2023

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