Notes / University Notes / Operating System / Chapter 11: File System Implementation

Chapter 11: File System Implementation

Created: 2025-12-16Updated: 2025-12-16

The same file system from below: the on-disk structures that make up a file, how blocks get allocated to it, and how free space is tracked.

File System Structure

I/O transfer between disk and main memory is done in units of blocks
one block(logical) can be one or more sectors(physical)
sector: typically 512 bytes
one OS can support more than one file system type
two design problem: interface to user programs and interface to physical storage (disk)
Layered File System
- API: read(fh, buf, size)
- Logical File System: menage metadata (directory structure, file attributes...)
- File Organization Module: logical $\to$ physical mapping (file blocks $\to$ disk blocks)
- Basic File System: read d1, c73, t5, s4 (disk driver interface) (disk, cylinder, track, sector)
- I/O Control Device Driver: control the physical device
- Devices: Seagate disk

File System Structure

I/O transfer between disk and main memory is done in units of blocks
one block(logical) can be one or more sectors(physical)
sector: typically 512 bytes
one OS can support more than one file system type
two design problem: interface to user programs and interface to physical storage (disk)
Layered File System
- API: read(fh, buf, size)
- Logical File System: menage metadata (directory structure, file attributes...)
- File Organization Module: logical $\to$ physical mapping (file blocks $\to$ disk blocks)
- Basic File System: read d1, c73, t5, s4 (disk driver interface) (disk, cylinder, track, sector)
- I/O Control Device Driver: control the physical device
- Devices: Seagate disk