Inode
Structure tracking a file’s sectors is called an index node
Overview
Inodes are stored in fixed-size array
- The size of the array is fixed when the disk is initialized and cannot be changed
- It lived in known location
- Metadata is smeared across it
- For indirect and double indirect blocks
- Index of an inode in the inode array is an i-number
- OS refers to files by i-number
- When file is open, inode is brought into memory
- Inode is written back when file is modified
Inode maps a file offset → a data block for its file - contains metadata about the file
- Permissions
- Access/modification/change time
- link count
How is a new inode allocated?
Each file requires a new inode
- If it is a new file, put in same cylinder group as directory
- If it is a new directory, use a different cylinder group