interesting filesystems

Kragen Sitaker
Wed, 7 Apr 1999 13:27:45 -0400 (EDT)

Just a collection of interesting filesystem links.  Most are for Linux.

I'll maintain this and organize it better if there's demand.  :)

Overlay filesystem, like union mounts:

Working Version Filesystem, storing everytyhing in CVS (IIRC) over the
network, compatible with NFS:
(Previously known as Pgfs, built on top of 'ofs' -- open filesystem.)

wofs, a WORM filesystem for SunOS (in German):

PerlFS, which lets you write filesystem drivers in Perl and run them in
. . . and is writing a Java backend so you can write
	Java fslets.

userfs, similar to PerlFS, but with backends in C++:  (
(previous versions, like, didn't work with libc6/glibc)
mailing list at
Originally by, Jeremy Fitzhardinge, who abandoned it in 1997

Lots of nice information at on filesystems and other
kernel things.

e2compr -- transparent compression for ext2fs -- is at or

Of course, there's Coda, which is similar to AFS, but supports
disconnected operation:

"Arla", a free implementation of AFS (working client, experimental kernel):

"Podfuk" (Czech for fiddle), another userfs/PerlFS/ofs equiv -- but
this time using Coda.  Includes fs-based decompression and untarring as

"AVFS" -- "A virtual filesystem" -- allows transparent tar, gzip, zip,
bzip2, and rar reading.  In C library, not kernel:

"docfs" -- "unified documentation sotrage and retrieval for Linux
systems" -- generates documentation on the fly.  Sort of like an
automounter for document formats.  Appears to have been conceived in
mid-1997, but not implemented:

"devfs" -- like Plan9's filesystem.  Basically an alternative to
"special files":

The standard for large file access in Unix:

The famed reiserfs, based on balanced trees, intended to allow storage
of many small files:

Log-structured filesystem projects: -- abandoned since 1998-10-02 at least -- central discussion point -- appears to be viable,
	but not yet in beta
	(by Christian Czezatke, originally by Adam of Yggdrasil?)

UDF, the DVD-ROM and packet-written CD filesystem:

Global File System, a 64-bit filesystem for shared disks:, body "subscribe gfs-announce" or "subscribe

Time Capsule Filesystem: intended to be decipherable without a specification,
useful for long-term archival:

TCFS, the transparent cryptographic filesystem (it talks NFS):
 (paper in German) ("subscribe tcfslist" in body)

vs3fs: experimental steganographic filesystem:
apparently has become "sfspatch" and "sfstools":

cfs: cryptographic filesystem: similar to tcfs.  Originally by Matt Blaze;
available from for USians. has information about it.

AtFS, "The Attributed File System" -- versioning, application-defined
arbitrary key=value metadata, C-library-based.  Part of "ShapeTools", a
software configuration management system.

Undelete for ext2fs:

Various foreign filesystems for Linux:
	Mac HFS:
	Windows NT NTFS:
	(Many others, of course, are included in the kernel.)

<>       Kragen Sitaker     <>
This is exactly how the World Wide Web works: the HTML files are the pithy 
description on the paper tape, and your Web browser is Ronald Reagan. 
  -- Neal Stephenson, at