Filesystem Limitations

This rather technical page arose out of research I was doing into file system limitations of various operating systems.

Maximum volume sizes, maximum file sizes, maximum number of files per volume, per directory or folder, and maximum lenght of filenames. I am putting this table on the web because I had great difficulty finding this information documented anywhere. Many people do not know these limitations, which many people never strike. There are still gaps and I would appreciate any feedback if you find errors or have additional information.

Notes:

1      Less if long filenames are used
2      Microsoft recommends turning off short filename support if there will be > 300,000 files per subdirectory
3      216 = 65,536, 232 = 4 GB, 241 = 2,048 GB = 2 TB, 264 = 16 ExaBytes (EB)
4      Windows XP can format FAT32 volumes up to 32 GB, but can read larger volume sizes if formatted by another operating system
5      FAT16 volumes larger than 2 GB are not accessible by DOS, Win 95/98/Me and other s as the maximum cluster size is 32 kB on these operating systems
6      Must use Windows Dynamic Volumes to create NTFS volumes over 2 TB in size
7      ext2 is limited to 2 TB file system on 32-bit systems
8      32,768 subdirectories per directory, and up to 100 Trillion files per directory, but limited to 10,000 – 15,000 files for performance reasons unless caching or something else is used
9      The pathname limit includes the filename, eg on Windows 98 if the pathname is 250 characters in length the filename may only be 10 characters long
10    There have been extensions to the original ISO9660 spec for CD-ROM file systems. ISO9660 is sometimes called CDFS in the Windows environment.
11    Initial ISO9660 supported only 8+3 filename length, CDFS extended this to 32 characters. Directory trees can be no more than 8 deep.
12    Joliet is an extension of ISO9660. Joliet is read as an 8.3 shortname on DOS/Win 3.1, MacOS and Unix although it supports filenames up to 64 characters (and longer in some implementations.
13    UDF requires a driver to be installed on Win 95/98/NT4 and MacOS
14    Romeo proprietary format from Adaptec EasyCD Creator never made an impact on the market
15    FAT12 is used on 5.25” floppy disks (3.5” disks used FAT16) and on disk volumes smaller than 16 MB
16    Maximum of 99 folders on ISO9660 volumes
17    Unix file system limits varies widely depending on the operating system and Unix kernel, and 32-bit or 64-bit implementations
18    r5 hash allows 1.2 million files before hash collisions occur on Reiser file systems v3.6