In sci.physics, John Gilmer

wrote
on Sat, 10 Jul 2004 10:53:27 -0400
:



Just another reason why FAT was obsoleted by HPFS which in
turn was obsoleted by NTFS.

I'l bite:

I think I understant FAT systems.

But the only thing I "think" I know about the NTFS is that, effectively, the
system first makes a record of what it is about to do, then it does it, and
then it either erases the original record or somehow marks it.

SO: can someone "explain" the NTFS to me. (Please don't tell me to "look
it up.")


NTFS stands for NT File System, presumably. (I've no idea what NT
stands for. Certain jokesters have their own opinions, mine among
them.)

A file system is a method by which the unorganized data in
a disk partition -- basically, a very long chain of blocks,
or perhaps a mapping from an integer (the logical block
address) to a fixed-size chunk of data (the block) -- can
be organized into something more appetizing to humans:
files, directories, symbolic links, or in Microsoft
parlance (perhaps), documents, folders, and shortcuts.
DOS 1.0's FAT filesystem didn't even have directories
(that was added in 1.1 or 2.0; I forget which). NTFS is
fairly sophisticated; it has, among other things:

- per-file locking (to the intense annoyance of UNIX and Linux
programmers, this appears to be on by default)
- resource streams a la Macintosh (which aren't apparently used yet?)
- Access Control Lists
- Unicode support
- Case-preserving filenames
- a master file table, which is where the small files live
- sparse files (files with "holes" in their blocklists -- a
useful capability in some contexts related to databases, AIUI)
- short file name capability for DOS backwards compatibility
- hidden files
- support for running a defragmenter while the volume is mounted.
(Don't ask.)

There are a few other capabilities but I'd have to look.

If you really do want to look it up, you can try
the Linux source code -- an NTFS implementation
is in the kernel under /usr/src/linux/fs/ntfs or
/usr/src/linux/Documentation/filesystems/ntfs.txt. It is
definitely not for the faint of heart. There should
be some documentation somewhere on Microsoft's website,
of course; again, I'd have to look.

HTH

--
#191,
It's still legal to go .sigless.