When you acquire new systems for your organization, you face the
challenging task of installing Windows NT, applications, and data on them.
Swapping floppy disks and CD-ROMs, entering information, changing defaults, and
performing the other required tasks to get an NT system up and running just
takes too much time, particularly when you have to do it for several systems at
once.
For example, say you need to set up 15 systems for new employees, each
system with the same hardware, running NT 4.0, and including 10 applications. In
addition, you must make the necessary changes to the Registry on each system for
the Explorer interface and security. Setting up the systems manually is costly
in time and productivity. Letting users install NT and applications for you
wastes their productive time and leads to installation errors. Cloning is the
answer.
Approaching Cloning
The goal of cloning is to create a duplicate system with all the original
system's interface changes, tweaks, installed software, and options. However,
each system you clone must be a unique system on the network. Merely copying all
the files with XCOPY.EXE won't work because a copied system has the same
security identifiers (SIDs) as the original for the operating system, machine
name, and shares. The problem with such copying is that to ensure connectivity
with servers, each cloned system must have unique SIDs, especially the machine
name. Also, the cloning process must be fast; if not, it isn't worth the effort.
And you need to be able to clone NT systems without incurring extra costs for
necessities such as software and licensing.
To meet these requirements, the best approach to cloning is to take a
currently set-up system, make sure it has the applications, data, and settings
you want, and duplicate that machine's setup (except for the SIDs) on other
systems. One cloning method is to use Computer Profile Setup (CPS), a set of
utilities in the Windows NT 3.51 Resource Kit that lets you create a master
system configuration that you can copy to other machines. However, CPS is
difficult to use and doesn't always create unique SIDs. Third-party cloning
products, such as Ghost from Binary Software and DriveCopy from PowerQuest are
alternatives. Such products work well for cloning Windows 3.x and Windows 95
systems. However, for NT cloning, these products have some limitations. For
example, these products can't deal with NT's requirement for unique computer
names and IP addresses, nor can they handle differences in hardware, drivers,
and settings. An easier, more reliable method is SYSDIFF.EXE, a tool on the
Windows NT Server 4.0 CD-ROM (documentation for SYSDIFF.EXE is in the NT 4.0
Resource Kit).
SYSDIFF.EXE
The SYSDIFF.EXE utility lets you clone system modifications, applications,
and changes--but not the NT operating system. You must install NT on the systems
before using SYSDIFF.EXE for cloning; I explain a method for combining
the NT installation and cloning process later. SYSDIFF.EXE can help make the
necessary interface changes and connections to the network and shares. It can
also help install application files and implement the necessary Registry changes
associated with those files.
You can use SYSDIFF.EXE to perform these tasks in two ways, both of which I
explain in this article. You can combine Registry changes and the binary files
required to run the applications, putting them into a difference file (a
file that identifies differences between the original and current configurations
of the system being cloned) and then copy the difference file to the new system.
Alternatively, you can use SYSDIFF.EXE to make only Registry changes. This
approach creates an .INF file. You then copy the files by performing a backup
and restore or by recording the files on a CD-recordable drive and copying them
to the target system. Whether or not you include all the programs and auxiliary
files, when you decide to clone your system, the most important part of the
operation is the Registry.
SYSDIFF.EXE Prerequisites
For SYSDIFF.EXE to work correctly, several things are necessary, including
- a master system with NT Server or Workstation 4.0 installed. You will make
necessary changes on and add applications to this system.
- a share on the server for the SYSDIFF.EXE application and auxiliary
files, with sufficient space for all the applications to be installed on the
master system. In this article, this share is in D:\BIN, shared as
\\SERVER1\SOURCE.
- SYSDIFF.EXE, which creates and applies the necessary files for cloning. It
is on the NT 4.0 Server CD-ROM in the SUPPORT\DEPTOOLS\platform
directory. Copy it to the share you've reserved on the server.
- the snapshot file, which SYSDIFF.EXE creates to record the current
system status (i.e., create the before picture).
- SYSDIFF.INF, which controls what SYSDIFF.EXE looks for when it
creates its snapshot and difference files. Copy this file from the CD-ROM to the
share.
- the difference file (i.e., the after picture), which SYSDIFF.EXE
creates and which includes the changes made to the Registry, application files,
and files associated with them.
- the target systems, which already have NT installed. You'll copy the
changes in the difference file to these systems.
If any of these parts are missing, preparing and implementing the clone
installations will not work.
Step-by-Step Cloning: The Difference File Method
Here are 12 steps for cloning NT systems, using SYSDIFF.EXE to create a
difference file that you'll copy to the target system.
- Install NT Workstation or Server 4.0 on the
master system. However, wait to install applications until step 5.
- At the master system, map a drive letter to
a share on the server (for example, X:\ is mapped to D:\BIN).