Rule Construction

The Rule Constructions dialog box allows you to configure a rule for the Device Imaging Work Assignment section. You can add multiple rules, and each rule can contain multiple filters.

Understanding rule logic is important in using this dialog box. For more information, see Rule Logic.

To configure a hardware rule:

Fill in the following fields and select or deselect the options:

Rule Name: This name is displayed in the rules listing on the Preboot Services page in the Device Imaging Work Assignment section. Make it descriptive enough that you can later remember its purpose.

Bundle to Apply: When a device is seeking work to be done, it scans the rules until it finds a rule where all of the rule’s filters match the device, then executes the bundle assigned to the rule. Each rule can be applied to only one bundle.

Because the rules, not the bundles, are listed in the Device Imaging Work Assignment section, you can apply multiple rules to a given bundle. So, a bundle has multiple chances to be selected for device imaging work.

When multiple rules are listed, the first rule with criteria to match a device causes that rule’s assigned bundle to be applied to the device.

If no rules match a device, then none of the applicable bundles are applied to the device.

PXE Kernel Boot Parameters: Select one of these two options:
- Use the Parameters Configured in Imaging Menu Options: This causes the rule to use the default boot parameters for the Management Zone.
- Use These Parameters: Only the boot parameters that you specify here are used for this rule.
Enabled: This is the only way that you can temporarily disable a hardware rule. It is enabled by default.

The rule’s status is shown by the first word in the work rules listing on the Preboot Services page. For example, Enabled - Asset Tag Rule.

Force Download: Forces the download of the assigned bundle, even if it matches the most recently installed bundle. By default, downloading the hardware rule is not forced.

By default, ZENworks® imaging does not reimage a machine containing the same image. This option allows you to force the image to be reapplied to the device. For example, you might want to refresh all of your lab machines for the next use of the lab.

IMPORTANT:Use this option cautiously. It can create an endless loop, because the option remains selected after an image has been applied. If you image a device that remains non-registered after it is imaged, it is reimaged with the same image over and over each time it boots. To prevent this, edit this hardware rule and deselect this option after you have imaged the applicable devices.
Using the Rule Logic fields and options, create the hardware rule expression using the following options:
- Add Filter: Adds the new filter at the end of the list of filters.
  
  Because the filter is added to the end of the last filter set, you cannot use this option to select which filter set to add it to. Use the Insert Filter option to add a filter into an earlier filter set.
- Add Filter Set: Adds a new set of filters, beginning with one filter in the set. The filter set order cannot be rearranged.
- Insert Filter: Allows you to insert a new filter either above or below the selected filter. This also enables to you specify which filter set to add a filter to.
- Delete: Removes the selected filters from the rule.
- Combine Filters Using: The default is to have filters ANDed and filter sets ORed. You can use this field to reverse these Boolean functions for the filters and sets.
  
  Using OR for filter sets means that all filters in a set must be matched to apply the rule, but any of the sets can be matched to apply the rule.
  
  Using AND for the filter sets means the reverse. At least one filter in each set must be matched for the rule to be applied.
An expression consists of a criteria option, operator, and value, and in some cases, a qualifier. For example:
```
RAM (in MB) =< 512 MB
```
RAM (in MB) is the criteria option, =< is the operator, 512 is the value, and MB is the qualifier.

If necessary, you can use NOT (in the first blank field with a down-arrow) to perform a logical negation of the expression. For example:
```
NOT RAM (in MB) =< 512 MB
```
In the above example, the rule is applied only to devices with less than 512 MB of RAM.

You can use more than one expression for the rule. For example:
```
RAM (in MB) =< 512 MB or
```
```
Hard Drive Size (in MB) < 20 GB
```
Hardware Type displays in the criteria options list only if you have previously configured a custom hardware type and saved it by clicking Apply at the bottom of the Preboot Services configuration page.

IMPORTANT:Be aware of the possibility of creating conflicting filters or rules. For example, if you specify a RAM condition in multiple filters, make sure the effective logical operators where each is configured makes sense for the megabyte values that you enter. In other words, if two filters are both required (ANDed), you would not want one filter to require exactly 512 MB of RAM and the other to specify at least 512 MB of RAM.
Click OK to exit the dialog box and place the new hardware rule into the Hardware Rules list box on the Preboot Services configuration page.