Alles Voor Internet / Tout Pour Internet/alles voor internet.iso/MacInternet™/Info/nfs-clients.txt

Internet Message Format | 1992-10-07 | 15.0 KB | [TEXT/UNIX]

Date: Wed, 7 Oct 1992 10:14:01 -0700 (MST)
From: [e-mail] (A virtually vegetal non-entity)
Subject: Re: Info-Mac Digest V10 #241

In article <[e-mail]>, it is written:
>
>Info-Mac Digest             Tue,  6 Oct 92       Volume 10 : Issue 241
>
>Today's Topics:
>
>      Need network software on Mac to connect UNIX's NFS (A)
>

I did a review of the two NFS clients for Macintosh for Digital
News (now merged with Digital News and Review).  You can read it in
DN, or (since DN is now unable to give reprints) here's the text:

NFS Client for Macintosh, Product Profile

by Joel Snyder
Opus One

+++++++++++++++
This should go into a "box" next to the story to explain what NFS
is and why the managers should care about it.  The actual story
begins after the next line of pluses.


What is NFS?

Every computing platform has its own way of sharing disk storage across
systems.  VMS has VAXclusters, and Digital's DFS (Distributed File System).
In the MS-DOS world, there are lots of contenders: Novell Netware, Banyan
Vines, and Microsoft LAN Manager (which Digital calls Pathworks for DOS),
to name a few.  For Macintosh computers, Appleshare was the first.  In the
Unix world, the most venerable and most popular is NFS, the Network File
System.  NFS was developed by Sun Microsystems during the late-1980s as a
way to link lots of inexpensive desktop workstations with Ethernet
interfaces and TCP/IP software to larger compute servers and disk farms.
NFS is one piece of Sun's answer to VAXclusters.

The general term for this  software is "distributed file system."   In the
distributed file system game, "server" always means the computer with the
disk on it.  "Client" is used to describe the systems that use the server's
resources.  On most minicomputers, a system can be both a server and a
client.  In Macintosh and MS-DOS systems,  the microcomputer generally is a
client, with many clients sharing one or two servers.

As distributed computing systems have grown, each of these distributed file
systems has grown out of its original environment.  So, we have Pathworks
on VMS (and Ultrix), which lets a VAX provide disk service to MS-DOS
systems running LAN Manager.  There are also Netware  servers for VMS and
Unix, Netware clients for Macintosh, Appleshare servers for VMS and Unix,
Appleshare clients for MS-DOS, and so on.  In this review, we'll
concentrate on NFS clients for the Apple  Macintosh.


Why would you use NFS?

NFS has two major advantages over all of the other client/server
distributed file systems: first, it's been implemented on every major
computing platform.  Microcomputer, minicomputer, and mainframe: all
support NFS client, and many support NFS server.  Second, it's cheap.   Not
only is the client software inexpensive, but it's also cheap to install,
cheap to maintain, and cheap to manage.  NFS was designed to be simple to
implement and simple to operate, and it lives up to that very well.  Once
you've got a TCP/IP network installed, adding NFS to most servers takes
only a few minutes.

NFS also has some disadvantages.  NFS normally runs on top of Sun's RPC
(Remote Procedure Call) software, and RPC normally runs over the UDP (User
Datagram Protocol) protocol in a TCP/IP network.  While most users don't
care about such things, there is an important implication: most TCP/IP
networks don't checksum UDP packets. That means that any data which is
corrupted in passing over a network won't be discovered as "bad" by NFS.
If your application calls for high levels of data reliability, you'll
probably want to think twice before choosing NFS.

NFS also doesn't support sophisticated file organizations and operations,
such as indexed files or record locking.  In the NFS world, these are left
to higher-level application packages.  Security in NFS is limited to
Unix-style user- and group-id mapping.

Nevertheless, NFS makes a lot of sense for many environments.  It provides
broad access to file-based data across all significant computing platforms.
It's designed for distributed operation, which makes it easy to build very
large networks.  And it uses TCP/IP, which is better supported than
transports such as Novell's IPX or Digital's DECnet.

+++++++++++++++


Macintosh users who wish to participate in NFS networks have two choices:
Pathway Client NFS (version 1.2)
>From The Wollongong Group (Palo Alto, California) and
NFS/Share (version 1.1.2)
>From Intercon Systems Corporation (Herndon, Virginia).   Both are
client-only NFS packages which allow a Macintosh to access files on NFS
servers across a TCP/IP network.    Because both Pathway Client NFS
and NFS/Share run over Apple Computer's MacTCP, they can coexist with a
wide variety of TCP/IP applications from various vendors on the same
Macintosh.

To put these products through their paces, we tested them in a fairly
heterogeneous environment: a Macintosh II running System 7.0.1
with two different Ethernet
boards. The NFS server was a clustered VAXstation 4000 Model 60 running
Multinet NFS Server from TGV, Inc (Santa Cruz, California).

Installation of either product is simple.  Pathway Client NFS is a control
panel document.
To install, simply drag a single file over the system folder, configure
MacTCP (if not already in place), and reboot.  More complex features, such
as an LPR server, an automatic mounter, and an SNMP agent, are part of the
software, and require additional configuration.

Installation of NFS/Share is slightly
more complicated.  It appears as a chooser document.  To install under
System 7, you have to manually place it into a special part of the system
folder, configure MacTCP, and then reboot.
NFS/Share then brings up a dialog box asking for a
Product Access Key, which long string of characters to enable your copy.
Future reboots don't require you to reenter the key.

Both products have simple
interfaces to mounting volumes.  Both look on the network for NFS servers
and list exported file systems for the user.  However NFS/Share was
the only product which could reliably mount an
NFS volume over a 9600 bps SLIP (serial line IP) link.  Pathway Client NFS
could not handle the wide area network link.
If that were all there is to it, this review would be a very short one.


Multi-System Environments a Problem

Unfortunately, it's not that easy.  For environments where several machines
of different types must access the same server, the Macintosh can be a big
problem.

The Macintosh has a file system which is distinctly different from most
other popular systems.  The combination of unusual file names, strange file
semantics, and a "single user" approach to disk volumes makes it very
difficult to emulate the Macintosh file system on any other computer.

Filenames are a good example.  Macintosh file names keep their case,
but are not case sensitive.  Names can be up to 31 characters long, and can
have any character except for the colon.  In order to retain file names,
each of the NFS clients has a convention for "converting" filenames to
their Unix equivalent.  Unfortunately, the convention each has chosen is
different, which means that you cannot mix Pathway Client NFS and NFS/Share
clients in the same network---they won't see the same file names.
If you can imagine what an MS-DOS client is going to do with any kind of
Macintosh filename, you'll begin to see how big a problem this is.

A second problem occurs in the handling of the "end of line" character in
files.  VAX/VMS, Unix, MS-DOS, and the Macintosh all have different ideas
of how lines are terminated in text files.  Pathway Client NFS provides
some tools to help deal with this problem, and NFS/Share simply ignores it.
When an NFS server is shared by clients using different operating systems,
this causes a big problem.  For example, editing a normal VMS file on the
server, Pathway Client NFS reads it just fine.  However, if any changes are
made to the file, the newly saved version isn't readable on the VMS system.

NFS/Share is even more difficult to deal with.  A file edited on the
Macintosh and saved back to server bears no resemblance to the original
file, with Macintosh control information added to the end of the file,
and possibility of a filename change.


Security

Because the Macintosh is considered to be a single user system, security is
simple.  As each NFS volume is mounted on the Macintosh, the Macintosh user
is asked for a username and password on the NFS server.  This
validates the Macintosh user, and gives all users of that Macintosh access
to files that the user/password combination has access to.

If this information is saved to disk, this opens up a typical security
hole: now, anyone with physical access to the Macintosh can access all the
files that this particular user has permissions for.   NFS/Share allows the
user to require the NFS server password to be entered at each boot. Pathway
Client NFS doesn't have this option.

An additional problem occurs in Macintoshes using System 7 Personal
FileShare: NFS volumes mounted on one Macintosh could be accessed by other
Macintosh systems on the same network.  Network managers installing and
configuring NFS clients on the Macintosh should make sure each user
understands the potential security holes.  Pathway Client NFS solves this
problem by not supporting Personal FileShare.

Another security problem is one of data integrity.  Neither NFS client
provides any guarantee of data integrity.  Any  requirements for data
integrity should be evaluated carefully before using Macintosh NFS clients.



Bells and Whistles

Pathway Client NFS has more features, and is more configurable than
NFS/Share.  Pathway Client NFS allows the user to specify different types
of filename mapping schemes, NFS read/write size (necessary for dealing
with some older gateways and equipment), a set of default privileges for
new files created on the server, and translation of the end-of-line
character to Macintosh style files.  Pathway Client NFS also offers an LPR
server, which allows a Macintosh to provide printing services to other
TCP/IP hosts which support the LPR/LPD protocol.

Pathway Client NFS also provides a simple text editor which refrains from
converting files into Macintosh format, and a separate automatic volume
mounter application.  We couldn't get this last piece to work.  For
NFS/Share, the automatic mounter is built into the basic application.

Both products include simple SNMP agents.


Performance

Performance of both NFS clients was slower than local hard disk access
times in most cases.  The graph [on this page???] compares times for three
operations: writing from a Macintosh client to the NFS server,  reading
>From the server by the client, and writing from one NFS server to another
NFS server via a Macintosh client.   This graph shows three products:
Pathway Client NFS, NFS/Share, and Digital's Pathworks, for comparison.  On
this graph, the Macintosh had an Apple Ethernet card installed.

A second set of timings were done with a Compatible Systems (Boulder,
Colorado) Ether2 Ethernet card.  Using this card, instead of the Apple
card, resulted in significantly better performance.  All operations were
about 15% faster.  In fact, Pathway Client NFS and NFS/Share were faster
than a locally connected hard disk for read operations of large files using
the Compatible Systems card.

In general, Pathway Client NFS operated faster than NFS/Share, in all
environments.  Naturally, these performance figures are based on a specific
configuration, and should be considered as rough guidelines rather than as
a detailed competitive analysis.



Recommendations

The Macintosh file system is difficult to deal with.  While NFS is a very
useful and almost universal distributed file system, combining the
Macintosh and NFS results in compromises for both.  An enthusiastic manager
might see NFS as the answer to compatibility dreams, but it's not to be so:
Macintosh systems do not share the same NFS server very well.

For specific environments and specific file sharing applications, both
products fit the bill very nicely.  Check the feature comparison chart
[below???] to see which is most appropriate for your network.   We found
both products to be robust.  We discovered fewer bugs in NFS/Share than
Pathway Client NFS.  Documentation for both products was satisfactory, but
not excellent. Technical support
was better from InterCon Systems than Wollongong Group, mostly because
their product development team advertises electronic-mail support of the
product.  Wollongong also offers a wide variety of support packages,
including pay-per-call and contract support.

NFS is not the best tool for distributing Macintosh file systems.  If all
you need to do is provide Macintosh-to-Macintosh file service, consider
using the Macintosh native file system, AppleShare, with Macintosh, VMS,
or Unix servers for best performance, lowest price, and fewest compromises.

Whatever you do, stay away from standard Apple Ethernet hardware.  Make
sure you test some of the newer and faster third-party Ethernet boards in
your own network.  You will probably save money, and may end up with better
performance to boot!






Executive Summary

. NFS clients allow Macintosh users to get access to NFS servers on
minis and mainframes using TCP/IP networks.

. Macintosh file system is difficult to translate into Unix or VMS, so
universal access to the same data isn't easy.

. Carefully test NFS clients in your environment to make sure that they do
what you need; other file sharing products may be better solutions for you.

. Can't mix Mac NFS clients on the same server, so a single vendor solution
is required.

. Performance generally not as good as local hard disk, but third-party
Ethernet cards can help.





Feature Comparison

Feature                    NFS/Share    Pathway Client

NFS client for Macintosh        X        X
Uses MacTCP                X        X
supports NIS                X
supports BWNFSD                X
supports PCNFSD                X        X
supports NFSAD                        X
System 7 aliases            X
SNMP agent                X        X
Automounting disks on startup        X        X
LPR Print Server                    X
Special editor for foreign files            X
Configure NFS read/write size                X
Time zone support            X        X



Products Discussed in this Review

Pathway Client NFS V1.2
The Wollongong Group
1129 San Antonio Road
Palo Alto, California 94303
415-962-7142
415-968-3619 (FAX)

$295 suggested retail, $177 educational


NFS/Share V1.1.2
InterCon Systems Corp
950 Herndon Parkway
Herndon, VA 22070
703-709-9890
703-709-9896 (FAX)
[e-mail] (email)

$295 suggested retail, $118 educational


Ether2 Ethernet Adapter
Compatible Systems Corp
4730 Walnut Street, Suite 102
Boulder, Colorado 80301
303-444-9532
303-444-9595 (FAX)

$295 suggested retail, $199 educational


Pathworks for Macintosh V1.1
Digital Equipment Corporation

Client license QL-YPH9W-AA, suggested retail $308, educational $154
Client media and documentation QL-YPCAA-H5/-HM, suggested retail $493
Server media and documentation QL-YPHAA-H5/-HM, suggested retail $430
(note: contact your local sales representative
for applicable discounts and order codes)



Joel M Snyder, 1103 E Spring Street, Tucson, AZ, 85719
Phone: [phone] (voice) .4095 (FAX) .4093 (data)
BITNET: jms@Arizona  Internet: [e-mail]  SPAN: 47541::telcom::jms
Yow!  Is my fallout shelter termite proof?