1. Linux and File Systems
What is a file system?

2. Linux and File Systems
What is a file system? It's simply a way to represent binary data on a block device

3. Linux and File Systems
What is a file system? It's simply a way to represent binary data on a block device
What makes one file system different from another?

4. Linux and File Systems
What is a file system? It's simply a way to represent binary data on a block device
What makes one file system different from another?
Journaling
Extended Attributes
Quota Support
Access Control Lists
Compression
Network Support
Handling of sparse files

5. File Permissions Three groups of flags: e.g.: rw-r--r--
First group is for the owning user
R for read
W for write
X for execute
Second group is for owning group
Third group is for everyone else

6. Directory Permissions
Three groups of flags: e.g.: rwxr-xr-x
First group is for the owning user
R for read files in the directory
W for writing of files in the directory
X for entering into the directory
Second group is for owning group
Third group is for everyone else

7. Access Control Lists
Used to allow more users/groups access to a directory or file
Command: setfacl -m u:rw-:<username> <file>
Also allows default permissions to be set on new files created in a directory
Generally requires the acl mount option

8. Extended Attributes Used to store additional metadata with a file
For example, Samba uses user.DOS_ATTRIB to store DOS attributes inside Linux extended attributes.
Generally requires the user_xattr option

9. Disk Quotas
Used to restrict how much data can be written to a mount point by a user or group
Stores its data within two files, aquota.user and aquota.group
Usually requires the usrquota and grpquota mount options

10. Mount Points, Inodes and Links
Strictly speaking, you don't mount a file system, you mount a block device that contains a file system.

11. Mount Points, Inodes and Links
Strictly speaking, you don't mount a file system, you mount a block device that contains a file system.
Inodes
Inodes are like indexes within a file system that contain the raw file data and additional metadata.

12. Mount Points, Inodes and Links
Strictly speaking, you don't mount a file system, you mount a block device that contains a file system.
Inodes
Inodes are like indexes within a file system that contain the raw file data and additional metadata.
Links (specifically hardlinks) point directly to the file. A file can have more than one hard link which links the file at different locations in the file system hierarchy.

13. Mount Points, Inodes and Links
Strictly speaking, you don't mount a file system, you mount a block device that contains a file system.
Inodes
Inodes are like indexes within a file system that contain the raw file data and additional metadata.
Links (specifically hardlinks) point directly to the file. A file can have more than one hard link which links the file at different locations in the file system hierarchy. Symlinks are a special file that points to another file or directory. Unlike hardlinks, symlinks can branch across file systems and can link to directories.

14. Network File Systems Deal with multiple access
Require all the same features as local file systems
File locking can become difficult on network file systems
Different levels of support:
Encryption
Authentication
Caching

15. Journaling Treat a file system like a database
Most file systems are now journaled
Handle error recovery much better