Filesystem limitations

POSIX defines the set of services a filesystem must provide. However, not all filesystems are capable of delivering all those services.

Filesystem Access date Modification date Status change date Filename lengtha Permissions Directories Hard links Soft links Decompression on read
Image No No No 255 Yes No No No No
RAM Yes Yes Yes 255 Yes No No No No
ETFS Yes Yes Yes 91 Yes Yes No Yes No
QNX 4 Yes Yes Yes 48b Yes Yes Yes Yes No
Power-Safe Yes Yes Yes 510 Yes Yes Yes Yes No
DOS Yesc Yes No 8.3d No Yes No No No
NTFS Yes Yes No 255 No Yes No No Yes
CD-ROM Yese Yese Yese 207f Yese Yes No Yese No
UDF Yes Yes Yes 254 Yes Yes No No No
HFS Yes Yes Yes 255g Yes Yes No No No
FFS3 No Yes Yes 255 Yes Yes No Yes Yes
NFS Yes Yes Yes h Yesh Yes Yesh Yesh No
CIFS No Yes No h Yesh Yes No No No
Ext2 Yes Yes Yes 255 Yes Yes Yes Yes No

a Our internal representation for file names is UTF-8, which uses a variable number of bytes per character. Many on-disk formats instead use UCS2, which is a fixed number (2 bytes). Thus a length limit in characters may be 1, 2, or 3 times that number in bytes, as we convert from on-disk to OS representation. The lengths for the QNX 4, Power-Safe, and EXT2 filesystems are in bytes; those for UDF, CD/Joliet, and DOS/VFAT are in characters.

b 505 if .longfilenames is enabled; otherwise, 48.

c VFAT or FAT32 (e.g., Windows 95).

d 255-character filename lengths used by VFAT or FAT32 (e.g., Windows 95).

e With Rock Ridge extensions.

f 103 characters with Joliet extensions; 255 with Rock Ridge extensions.

g 31 on HFS.

h Limited by the remote filesystem.