Date: Sun, 2 May 1999 15:40:24 -0700
From: Nick Moffitt (
Subject: [ [Pigdog] interesting filesystems]
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Filesystem craziness follows:

----- Forwarded message from Kragen Sitaker ( -----

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

This is version 2. Added wrapfs, audiofs, more userfs stuff.

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

Overlay filesystem, like union mounts:

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

audiofs for Linux, like on SGIs, lets you access an audio CD as a filesystem containing audio files:

'wrapfs' is a flexible fs, ported to Linux, FreeBSD, Solaris, by amd's author:
> My research Web page is:

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

PerlFS, which lets you write filesystem drivers in Perl and run them in userspace:
. . . 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
More info (working version for Linux 2.2.6) at

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 applications:

"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 gfs-devel"

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 <>
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----- End forwarded message -----

"The software is intended to be as unobtrusive, unintrusive and unconstraining as possible. In software as elsewhere, good engineering is whatever gets the job done without calling attention to itself." -- Cynbe ru Taren, on Citadel (