Summary: Translucent File System

From: Doug Neuhauser (
Date: Thu Aug 02 1990 - 13:58:48 CDT

Summary: Use of the Translucent File System under SunOS 4.1.

I got a variety of responses, but the most complete was from Earle Poseur,
and I am enclosing it for reference:


>Has anyone used the Translucent File system that is SUPPOSEDLY available
>under 4.1 SunOS?

It's not `supposedly available'; it is available (as long as `options TFS'
and `options LOFS' are in the kernel configuration file for the currently
running kernel, that is). I'm using it right now:

poseur:2:30 [/tmp] % mount | egrep -v 4.2
yehtmae:/export/vol/X.V11R4 on /usr/share/src/local/X.V11R4 type nfs (rw,hard,intr,noquota)
/ on /tmp_mnt/Tfs_native type lo (rw)
/tmp_mnt/Tfs_empty on /usr/share/src/local/X.V11R4 type lo (rw)
/usr/share/src/local/.X.V11R4-build on /usr/share/src/local/X.V11R4 type tfs (rw,bg)

I mount my vanilla X11 R4 source tree from my Sun386i onto my Sun-3, and then
I do a TFS mount of another directory heirarchy (based at the directory
/usr/share/src/local/.X.V11R4-build) on top of that NFS mount. When a TFS
mount is done, it automatically adds the `/ on /tmp_mnt/Tfs_native' loopback
mount as well.

>I have several applications for it (local vs global
>manpages being one of them), but there appears to be a dearth of documentation
>on it, (and it may actually not even exist?). In particular:
> 1. The man pages say that the daemon tfsd is started by inetd,
> but I can't find any reference in /etc/inetd.conf or /etc/services
> to the program OR network service number and protocol that
> it should use.

Here's the /etc/inetd.conf entry:
# The TFS server provides the ability to do TFS filesystem mounts.
tfsd/1-2 dgram rpc/udp wait root /usr/etc/tfsd tfsd

> 2. The 4.1 Installation manual says to see the System and Network
> Admin manual for a complete description, but I don't find any
> description.

Yep. Bug in the documentation. An oversight; the TFS documentation didn't
make it into the System and Network Administration manual like the Install
manual claimed.

> 3. Is is unclear whether the front writable directory must be a
> separate file system or whether it can be a directory on a currently
> mounted file system.

It can be a directory on a currently mounted filesystem, as per my example
above. Here's my /etc/fstab:

/dev/sd0c /usr/src/local 4.2 rw 1 6
yehtmae:/export/vol/X.V11R4 /usr/src/local/X.V11R4 nfs rw,hard,intr,noquota 0 0
/usr/src/local/.X.V11R4-build /usr/src/local/X.V11R4 tfs rw,bg 0 0

Here's the end of my /etc/rc:

mount -vat tfs

exit 0

Given this scenario, I can still always refer to `/usr/src/local/X.V11R4' and
below as I would normally; any changes/compilations/etc. to that heirarchy is
really made in /usr/src/local/.X.V11R4-build and below. I made that TFS mount
point a `dot' directory name so that it would be more hidden. I never need to
refer to that directory tree by name, I see the virgin source tree *and* any
changes made to it, as if I'd done it directly in that tree. Greatest thing
since sliced bread :^)

        - Greg Earle
          Sun Microsystems, Inc.
          JPL on-site Software Support Engineer
          earle@poseur.JPL.NASA.GOV - or - earle@Sun.COM


Thanks to:

"Anthony A. Datri" <convex!>
mailrus!umich!dgsi! (Brian Kelley/1000000)
Mike Pearlman <>
Kerien Fitzpatrick <>
Todd Pfaff <todd@flex.Eng.McMaster.CA> (Greg Earle - Sun JPL on-site Software Support)
edsr! (Jim Niemann)
dgsi! (Paul Haas/1000000)

- Doug Neuhauser,, (818)356-3993

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