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File Systems— NTFS versus Ext2FS . Yingfei Wang Course: Operating Systems Instructor: Prof. Anvari. 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
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File Systems— NTFS versus Ext2FS Yingfei Wang Course: Operating Systems Instructor: Prof. Anvari
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
Windows NT NTFS (NT File System) Linux Ext2FS (Second Extended File System) File Systems
NTFS Structure • Sector • Smallest physical storage unit on disk • Cluster • Disk allocation unit for file • Volume • Disk partition formatted for use by file system
Ext2FS Structure • Block • Smallest file allocation unit • Block groups
Partition boot sector Boot startup info Volume layout info System file Master file table File/folder info Available space info File area Volume Layout of NTFS Partition Boot sector Master File table System files File area
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
Number of file system supported • Linux • 32 • EXT, EXT2, XIA, MINIX,UMSDOS, MSDOS, VFAT, HPFS, SYSV, SMB, etc • NT • 3 • FAT, NTFS, OS/2
Virtual File System in Ext2 FS User process System call System calls interface VFS Linux Kernel DOS FS Minix FS Ext2 FS Buffer Cache Device Driver I/O request Hardware Disk Controlor
NTFS • Sorry!
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. Security
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 Recoverability