UFS (Unix File System)

1. Superblock:

The superblock contains metadata about the file system, including:

• File System Size:

  • Total size of the file system in blocks.

• Block Size:

  • Size of each block (commonly 4096 or 8192 bytes).

• Fragment Size:

  • Minimum allocation size for small files.

• Free Block Count:

  • Tracks the number of free blocks.

• Free Inode Count:

  • Tracks the number of free inodes.

• Cylinder Groups:

  • Divides the file system into groups of cylinders for efficient allocation.

2. Cylinder Groups:

UFS divides the disk into cylinder groups, each containing:

• Superblock Copies:

  • Backup of the file system's superblock for redundancy.

• Block Bitmap:

  • Tracks the allocation status of blocks in the group.

• Inode Bitmap:

  • Tracks the allocation status of inodes in the group.

• Inode Table:

  • Stores metadata for files and directories.

• Data Blocks:

  • Contains actual file and directory data.

3. Inode Structure:

Each file or directory in UFS is represented by an inode, which contains:

• File Type and Permissions:

  • Indicates whether it's a file, directory, or special type.

• File Size:

  • Size of the file in bytes.

• Timestamps:

  • Tracks file creation, modification, and access times.

• Pointers to Data Blocks:

  • Includes direct, indirect, double indirect, and triple indirect pointers.

4. Fragments:

UFS uses fragments to efficiently store small files. Fragments are smaller units within a block, reducing wasted space when storing small files.