1. File Systems— NTFS versus Ext2FS Yingfei Wang Course: Operating Systems Instructor: Prof. Anvari

2. 2 File Management System A set of system software that provides services to users and applications in the use of files Functions: Identify and locate the selected file Directory management Enforce user access control Translate user command into file manipulation commands Optimize performance File allocation, disk scheduling

3. 3 File Systems Windows NT NTFS (NT File System) Linux Ext2FS (Second Extended File System)

4. 4 NTFS Structure Sector Smallest physical storage unit on disk Cluster Disk allocation unit for file Volume Disk partition formatted for use by file system

5. 5 Ext2FS Structure Block Smallest file allocation unit Block groups

6. 6 Capabilities NTFSExt2FS Max FS size2 TB4 TB Max file size4GB – 64GB2 GB File nameUp to 255chars Storage sizeVariable Clusterfixed block

7. 7 Volume Layout of NTFS Partition boot sector Boot startup info Volume layout info System file Master file table File/folder info Available space info File area Partition Boot sector Master File table System files File area

8. 8 Master file table FileMFT position Descriptionlocation MFT0File for tracking files on volume LCN000 MFT mirror1Metadata copy… Log file2Transaction record… ………… User file 1nFirst file, R, …LCN1668 Directory 1n+1First directoryLCN1888

9. 9 Physical Layout of Ext2FS Superblock: contains info about file system Group descriptor: contains info about each group Inode: contains info about each file and directory

10. 10 Inode Structure

11. 11 Number of file system supported Linux 32 EXT, EXT2, XIA, MINIX,UMSDOS, MSDOS, VFAT, HPFS, SYSV, SMB, etc NT 3 FAT, NTFS, OS/2

12. 12 Virtual File System in Ext2 FS User process Minix FSDOS FSExt2 FS System calls interface VFS Buffer Cache Device Driver Disk Controlor I/O request System call Linux Kernel Hardware

13. 13 NTFS Sorry!

14. 14 Security NTFS supports file-level security Degrees of permissions include R, W, D, P, O Protection against unauthorized physical access is better than FAT Still susceptible to physical access if some utilities like NTFSDOS is used Does not support file encryption EXT2fs Supports different levels of security Can prevent unauthorized access.

15. 15 Recoverability NTFS: Use log file to record the changes to volume redo or undo Mirror MFT for back up Support hot fixing disk sectors Ext2fs: Also offer logging of system transactions Every block group has a replicated control structure for backup

16. 16 Windows, Linux, Automobiles, etc.