From: N.Perry@massey.ac.nz (Nigel Perry)
Subject: WARNING: NetWare for the Mac may DAMAGE YOUR FILES
Reply-To: N.Perry@massey.ac.nz
Organization: School of Maths & Info. Sci., Massey University, Palmerston North, NZ
Date: Thu, 21 Jan 1993 22:41:43 GMT


WARNING: Novell NetWare for the Mac DOES NOT WORK CORRECTLY
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Software: Novell 3.11, NetWare for the Mac 3.011, System 7.0.1*,
System 7.1

Non-Technical Description:

A design feature of Novell NetWare for the Mac means that is DOES NOT
provide a "transparent" file system to Mac users as does a standard
AppleShare server. This feature can cause problems, such as breaking
QuickTime and backup systems. It's full effects are not known. You may
use NetWare without any problems, much software will not be affected
by the feature, but other software WILL and the damage may not be
noticed immediately (in our case it was not until Apple NZ was
demonstrating some of our software that the bug appeared and broke the
demo :-().

Note the careful use of the word "feature" above. Currently Novell
seem to argue that the design decision was reasonable, "It is not such
a bad decision considering the number of DOS clients compared to
Macintosh (NetWare) clients." (sic when you consider they're talking
about NetWare for the Mac!), and that Mac application writers should
attempt to program around their "feature"; "Also, it is MUCH easier to
change the client's side rather than on the server's side (please do
not lose sight of the absolutely HUGE task of changing time stamp
formats on the server side)."

Novell are looking at the feature but will give no details of when it
may be fixed.

Technical Detail:

NetWare changes a file in two ways when copied onto a NetWare volume:

1) The modified time of the file is truncated to an even number of
seconds.

2) The created time is set to (an even approximation of) the current
time, thus you get a file with a modifed time EARLIER than the
creation time (maybe as new releases of PC software come out PC users
are used to the sensation of time going backwards :-))

These two changes can cause potential havoc to QuickTime, backup
systems and compiler "make" systems. Whether they do cause problems
depends on your software and how you use it. We have had problems with
QuickTime and backup but our compiler systems (MetroWerks Modula-2)
seems to be working (though we havn't finished testing yet).

Novell have suggested that the problem could be avoided by performing
the time stamp corruption manually using ResEdit or a specially
written program. We went to the trouble of writing a "drag'n'drop"
application to perform the corruption on Mac & normal AppleShare
resident files based on this information from Novell. Unfortunately we
didn't know about (2) above which stops the method from working and so
a application (which uses QuickTime) still broke after being copied to
a NetWare volume.

How To Reproduce the "Feature":

This is how to reproduce the feature using QuickTime, you will
require: (A) an application to play & copy QuickTime movies (e.g.
Simple/Movie Player from Apple) (B) A QuickTime movie (C) An
application or DA into which to paste your movie (the QT compatible
Scrapbook will do). All these should reside on a local Mac HD or on a
normal AppleShare volume.

1) Open B with A and copy B to the clipboard.

2) Open C and paste B from clipboard.

3) Play B from within C.

4) Move both B & C to another location on your local Mac HD or normal
AppleShare volume.

5) Open C again and play B. QuickTime will search for B as you've
moved it.  Once found (probably very quickly) it will play.

6) Move B onto your NetWare volume. Remove the original (i.e. kepp
just the copy on NetWare).

7) Open C again and play B. QuickTime will search for B and FAIL to
find it. Manually locate B using QuickTime's dialog and select it.
QuickTime will report "not a valid movie file" :-( :-(

Note B is actually a valid file and you can repaste it into C, but
every time you move B off the NetWare volume and back again (or onto
another NetWare volume) the playback will break and YOU'LL HAVE TO
REPASTE.

The above occurs as NetWare is corrupting the timestamps on the file
which QuickTime uses to check the file is the correct one. Any program
which relies on timestamps (backup systems, compiler make's) may fail
for the same reason if files are ciopied to NetWare volumes.

Advice:

1) FLAME Novell.

2) Don't use NetWare.

3) FLAME Novell.

4) If you must use NetWare, check VERY carefully things are working OK
- especially your backups...

5) FLAME Novell.

6) If you use QuickTime FORGET Novell.

7) FLAME Novell.

8) Wish somebody else had brought USL? Will SV5R5 have "improved" 8
character/3 char extension filenames. After all they work for DOS...


-- 
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Dr Nigel Perry                    Email: N.Perry@massey.ac.nz
Department of Computer Science    Tel: +64 6 356 9099 ext 8900
Massey University                 Fax: +64 6 350 5611
Palmerston North
New Zealand