Ayşegül AYHAN & Can KOÇOĞLU Operating Systems’ File Systems

OUTLINE  What is the file system ?  File systems under Unix and Unix - like systems ext2 (Linux) ext3(Linux) Reiser FS (Linux)  File Systems under Mac OS X HFS - Hierachical File System HFS+ -Hierachical File System Plus  File Systems under Microsoft Windows FAT (File Allocation Table) FAT 32(File Allocation Table) NTFS(New Technology File System)  Conclusion Compare of these file systems with tables

What is file system? is a method for storing and organizing computer files make data easy to find and access them.

File systems under Unix and Unix - like systems one root directory, and every file existing under it. programs, device drivers, documents and spreadsheets, keyboard, etc. are files in Unix. avoids becoming an ungainly mess.

 This is how it works. An example from real life 

Linux is also an Unix-like Operating System ext 2 ext 3 reiser FS

ext 2 Previlages can be given to each of User, Group, Others. file system which proved itself Max file size 2 gb Max char size 255 chars Max volume size 4tb efficient if 4K blocks are used journal with ext3. Fullness of the disk not affects speed.

ext3 Almost same as ext2 but journal property added. So it is called journalled file system.

Reiser FS journaling property Max file size 8 tb Max volume 16tb High performance Especially small files but not much healthy..

File Systems under Mac OS X HFS Hierachical File System HFS+ Hierachical File System Plus

HFS Hierachical File System Similar MS-DOS and Unix with subdirectories Volume names max 27 chars. file names max 31 chars upper and lower case names unimportant All characters can be used, such as :, ?, \ … has two forks ; data fork, resource fork..

HFS + is developed version of HFS

File systems under Microsoft Windows MS-DOS FAT 12 (File Allocation Table) FAT 16 (File Allocation Table) FAT 32 (File Allocation Table) NTFS(New Technology File System)

MS DOS Only Intel platforms Not support multi-programming Version 1 – only single directory Version 2- more directories (hierarchical)

FAT 16 FILE ALLOCATION TABLE introduced way back with MS–DOS to handle files floppy drive minor modifications over the years can handle hard disks, even file names longer than the original limitation.

FAT 12 First version of FAT system Max file size 32 MB File name size 255 MB Max valume size 32 MB

FAT 16 Advantages MS-DOS Unix and Windows accept Has saving succesfull program to resque folders Has inauguration floppy if computer is locked To accesing data fast partitions < 256MB Disadvantages Max folder GB max size to folder doesn't support compression, encryption Lack of security…

FAT 32 FILE ALLOCATION TABLE enhanced version of the FAT used on drives from 512 megabytes (MB) to 2 TB partition limit is approximately 128GB can be accessed Win95B (OSR2, OSR2.1), Win95C (OSR2.5), Win98, Win98SE, WinME, Win2K and WinXP not accessed by DOS, Windows 3.x and Windows NT 4.0 majority of systems are formatted with FAT32 as the default.

FAT 32 Advantages  Acceptable all operating systems  more efficient for 64 MB and less than 64 MB memory  more faster if folder is small or not to big.  Comparing to NTFS hard disk head moves less.Because of that it works more efficiently on slower hard disks. Disadvantages  much more slower directories has too many files  Fragmantation performance  Should disk fregmantation frequently  hard to access big files  One file size only 4GB.

NTFS New Technology File System introduced with first version of Windows NT completely different file system from FAT provides for greatly increased security, file–by–file compression, quotas, and even encryption

NTFS Advantages System performance does not effect disorganisation File size performance Small file -->fast accessing Disadvantages not suggested for less than 64MB memory hard disk fast is low NTFS performance than FAT

Conclusion

Comparison of File Systems Limits

Comparison of File Systems Metadata

Comparison of File Systems Features