Linux File Systems

Presented By:

Dan AirdTyler Benson

Michael MooreBrad Yates

A. General Linux File Systems1. File Structure2. Supported File Systems 3. Inodes4. Drivers

B. UnionFS1. Structure2. Uses2. How it works

Linux File Systems

● Tree like structure● Unified File System

– Has one root (/)– (Windows has a different root for each

device: A, B, C, D…)

Linux File Structure

This could be a network

drive

This is in Memory

Multiple file systems, same directory structure.

• 9p2000• ADFS• AFS• Amega FFS• Amega SFS• BeOSFS• BFS• CIFS• CODAFS• CramFS• EFS• ext2• ext3• FAT16• FAT32• Free Vx FS

• GFS• GFS2• HFS• HFS+• HugeTLB• ISO 9660 (CD

ROM)• JBD• JFFS• JFFS2• JFS• MINIXFS• NCP• NFS• NTFS

• OCFS2• OS2 HPFS• PROCFS• QNX4• Reiserfs• ROMFS• SHMFS• SMB• SquashFS• UDF• UFS• UNIONFS• XENIX FS• XFS• Many other through

FUSE

Supported File Systems

● Stores basic information about a file, directory or other file system object

● Identified by an inode number● Fixed number of inodes in a file system● Inode can be identified using “ls -i”● Inodes do not include filenames, instead

relies on a link structure

Inodes

What is stored in an inode?

● User and Group ownership● Access mode● File type

How do inodes work?

● Indexes a table of inodes in a known location

● Using the inode number the kernel can access the contents of the inode including data pointers

Data Structure

● http://en.wikipedia.org/wiki/Inode

Device Drivers

● Built into the kernel● Interface between kernel and device

Linux Device Drivers

● http://mail.opensolaris.org/pipermail/install-discuss/2007-January/001577.html

UnionFS

What uses UnionFS?

● Knoppix since v3.8● Ubuntu LiveCD (Hoary)● Da[a-z]{2} Small Linux● Most Live CDs