Limitations of snAppShot

Now that you know how snAppShot works and understand some of its advanced features, you need to understand its limitations. snAppShot is a very powerful tool; however, it cannot be used for the tasks described in the following sections.

Capturing Install Logic

snAppShot is unable to capture the "logic" of an installation involving choices based on existing hardware, software, or other settings. For example, if the application's setup program installs a particular video driver or modem setting file to a workstation, these settings might not be valid when transferred to another workstation.

The following sections describe some of the things you should be aware of when using snAppShot to create application packages.

Hardware Specific Drivers

Some applications query the computer system to determine what hardware is installed and only install necessary drivers for the hardware that actually exists. This often results in problems if you distribute the application to clients that do not have the same hardware as the computer in which the application package was created. You can use the hardware inventory feature of ZENworks for Desktops, discussed later in this book, to quickly determine what specific hardware is installed on clients.

Available Disk Drives

Occasionally, an application install prompts the user to input additional paths of locations to store files. When you use snAppShot to create an application package, make certain that any additional paths you specify, both local and network, exist on all clients you want to distribute the application to. For example, if you specify a path on the D: drive, all clients must have a D: drive on their computer. If necessary, you can use macros and user prompts when distributing the application to handle this; however, that must be defined in the Application object.

Prerequisite Drivers and Applications

Another thing you should watch for when creating application packages using snAppShot is prerequisites for application installs. For example, if the application needs to determine which version of DirectX is installed on the computer, it might determine that the current version is correct and then not install needed DirectX drivers. This results in the drivers not being included in the Application object. If a client that is receiving the application from ZENworks for Desktops does not have the correct version of DirectX drivers, the application might not function properly.

Guaranteeing Impact on All Workstations

Although, you can use snAppShot to install or upgrade applications on all workstations, it cannot guarantee the impact the application install or upgrade will have on all workstations. The following sections describe some rare occasions when an application distributed to a client might result in problems.

Conflicting Local Applications

It is possible that an application distributed with ZENworks for Desktops could conflict with a local application that was installed by the user of that workstation. For example, you distribute a corporate virus scanner to all workstations. An existing application then cannot open files correctly because the virus scanner believes it is a virus that is trying to modify the files.

Most companies have some sort of standard for applications that can be installed on clients. This standard usually ensures that applications being distributed with ZENworks for Desktops do not conflict with any other applications on the users' systems.

Specialized Shared DLLs

When an Application object is delivered to a workstation, it can be configured to copy files only if they are newer. This usually protects shared DLLs because the older functionality is usually available in newer versions.

However, some applications have DLLs that have functionality written specifically for them. This functionality does not exist in newer versions, and, if they are overwritten with a newer file, the application they supported might no longer function.

Hardware Requirements

Many applications are written for computer systems that have a high level of CPU speed, RAM, video memory, disk speed, and so on. If this type of application is distributed down to a client workstation that does not have the hardware capability to support them, they will not function properly.

This potential problem can be controlled somewhat by configuring the Application object to check for hardware levels before installing (discussed in the next chapter). You can use the hardware inventory feature of ZENworks for Desktops, discussed later in this book, to quickly determine what hardware is installed on clients.

Imaging an Entire Workstation

snAppShot is designed to record changes made by a single application install, and therefore, it cannot image an entire workstation for disaster recovery purposes. When snAppShot discovers a workstation, it only saves some information about the files, such as the date, time, and size of the files. It does not save a copy of all the files on the workstation.

If you have a need to image an entire workstation, refer to Chapter 14, "Imaging a Workstation."