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Schedule a top-down discovery by Service Mapping

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Schedule a top-down discovery by Service Mapping

After Service Mapping discovers configuration items (CIs) belonging to your application service for the first time, it then rediscovers CIs to find changes and updates. Create or modify discovery schedules to control how often Service Mapping rediscovers services or CIs.

Before you begin

Define your application services prior to defining discovery schedules for discovering CIs which are part of these services.

When creating a schedule for CI types or specific CIs, make sure that at least one application service containing the relevant CI is in the operational state.

Role required: sm_admin

About this task

When you define a new application service, Service Mapping performs discovery of all CIs that participate in this application service and creates its map. After the initial mapping is complete, Service Mapping regenerates application service maps regularly by rediscovering CIs making up an application service.

By default, Service Mapping is preconfigured with these generic schedules:
All Applications
This schedule triggers the top-down discovery of all CIs of the application type [cmdb_ci_appl].
Load Balancer Service
This schedule starts the top-down discovery of all CIs of the load balancer service type [cmdb_ci_lb_service]
The generic schedules trigger discovery of all applications and load balancer services in your organization once a day. Typically, these preconfigured schedules are enough to update information for application services. However, if your organization needs to discover specific CIs or services more frequently, you can create the following custom discovery schedules:
Table 1. Schedule types for top-down discovery
Schedule type Description Example
Services Service Mapping discovers all CIs belonging to certain services that answer filtering criteria. In your organization, some application services are more critical than others and it is important for you to rediscover such services with high criticality more frequently. Create a custom discovery schedule to discover all services with the business criticality value set to most critical.

Alternatively, certain services in your organization are undergoing changes more often than once a day. You may want to create custom schedules to rediscover such services more frequently.

You can also create a schedule of this type to discover application services in a sub-production instance, where services are not in the operational state yet.

Services belonging to a group Service Mapping discovers all CIs belonging to services assigned to groups that answer filtering criteria.

Service Mapping discovers only services located directly inside the group that answers defined filtering criteria. Service Mapping does not discover services inside embedded groups.

Notice that you can define schedules based on service groups, even if your role does not have access to these service groups.

In a distributed organization with offices in several geographic locations, you may want to create a custom discovery schedule to rediscover services in one of these locations. For example, one schedule can trigger rediscovery of all services relevant for the EMEA site at 7am GMT, while another schedule can start rediscovery of services for the US headquarters at 7am PT.
For CI types Service Mapping discovers all CIs belonging to this type. Some CI types are prone to more frequent changes and updates than others, so you can manage the load by adjusting the discovery schedule to match the nature of each CI type.

When you define discovery schedules based on CI types, several schedules may apply to the same CI. To avoid discovering the same CIs more than once, the most specific schedule always has precedence. For example, if you create separate discovery schedules for a parent CI type and its child CI type, CIs belonging to the child CI type are discovered using its dedicated schedule. At the same time, if there is no schedule for a child CI type, the parent CI type schedule is used to discover the child CIs.

This schedule discovers only CIs belonging to application services in the operational state.

If you modify Apache Web server settings more often than you update your applications, you may want to discover Apache Web servers them more frequently than other CIs. In that case, create a custom discovery schedule for Apache Web server.
Specific CIs Service Mapping discovers only one CI that you specified for this schedule.

If you define a discovery schedule for a specific CI as well as a schedule for the CI type to which this CI belongs, Service Mapping uses the schedule for this specific CI, and not the generic schedule for its CI type.

This schedule discovers only CIs belonging to application services in the operational state.

For rare cases of rediscovering a specific CI that causes discovery errors frequently.

Having customized discovery schedules also allows you to avoid redundant stress on your infrastructure.

Part of discovering an application CI is identifying its host. Service Mapping checks if the device hosting this application CI exists in the CMDB. For a load balancer service, Service Mapping checks if the load balancing device hosting this load balancer service exists in the CMDB. If not, Service Mapping triggers Discovery to perform the horizontal discovery. As a result, Discovery performs host detection and updates the information on hosts in the CMDB. If necessary, you can manage the schedules that trigger horizontal discovery as described in:

Procedure

  1. Navigate to Service Mapping > Administration > Discovery Schedules.
  2. To create a custom discovery schedule, click New.
    Or

    To customize the generic schedule for all application CIs, click All Applications or Load Balancer Service.

    The Discovery Schedule page opens.

    The Discovery Schedule form for top-down discovery.
  3. In fresh install or reset instances, fill in the fields as follows:
    Table 2. The Discovery Schedule form in fresh install or reset ServiceNow deployments
    Field Description
    Name For a new specific schedule, enter a unique and descriptive name.
    Discover By default, the value for this field is Service, indicating that you are creating a top-down discovery schedule. You cannot change this value.
    Discover by For a new specific schedule, select CI Type.
    Note: In some special cases, you can create a schedule just for one specific CI. To do so, select Specific CI.
    CI type This field is available when CI type is selected from Select Discovery. For a new CI type-based schedule, select the relevant CI type from the list.
    CI This field is available when Specific CI is selected from Select Discovery. For a new schedule for a specific CI, select the relevant CI from the list.
    Filter Services to Discover This field is available when Service Attributes is selected from Select Discovery. Use the filter to create the filtering criteria for services. Service Mapping discovers only services that answer the defined criteria.
    Filter Groups to Discover This field is available when Service Group Attributes is selected from Select Discovery. Use the filter to create the filtering criteria for service groups. Service Mapping discovers only services belonging to the groups that answer the defined criteria.
    Active Select the check box to enable this schedule. If you clear the check box, the schedule is disabled, but you can still run a discovery manually from this form, using the configured values.
    Max run time Set a time limit for running this schedule. When the configured time elapses, the remaining tasks for the discovery are canceled, even if the scan is not complete. Use this field to limit system load to a desirable time window. If no value is entered in this field, this schedule runs until complete.
  4. In upgraded deployments, fill in the fields as follows:
    Table 3. The Discovery Schedule form in upgraded ServiceNow deployments
    Field Description
    Name For a new specific schedule, enter a unique and descriptive name.
    Discover By default, the value for this field is Service, indicating that you are creating a top-down discovery schedule. You cannot change this value.
    Service discovery For a new specific schedule, select a schedule type as described in Table 1.
    CI type This field is available when CI Type is selected from Select Discovery. For a new CI type-based schedule, select the relevant CI type from the list.
    CI This field is available when Specific CI is selected from Select Discovery. Select the relevant CI from the list to create a discovery schedule for this CI.
    Filter Services to Discover This field is available when Service Attributes is selected from Select Discovery. Use the filter to create the filtering criteria for services. Service Mapping discovers only services that answer the defined criteria.
    Filter Groups to Discover This field is available when Service Group Attributes is selected from Select Discovery. Use the filter to create the filtering criteria for service groups. Service Mapping discovers only services belonging to the groups that answer the defined criteria.
    Active Select the check box to enable this schedule. If you clear the check box, the schedule is disabled, but you can still run a discovery manually from this form, using the configured values.
    Max run time Set a time limit for running this schedule. When the configured time elapses, the remaining tasks for the discovery are canceled, even if the scan is not complete. Use this field to limit system load to a desirable time window. If no value is entered in this field, this schedule runs until complete.
  5. (Optional) For a discovery schedule based on service attributes, click View Selected Services to preview the list of services that answer the filtering criteria you entered. Click Close.
  6. (Optional) For a discovery schedule based on service group attributes, click View Selected Groups to preview the list of groups that answer the filtering criteria you entered. Click Close.
  7. Define the rediscovery frequency by selecting the relevant option from the Run list:
    Table 4. Discovery schedule run options
    Run option Description
    On Demand Does not run on a schedule. Click Discover now to run Discovery. This is the default option.
    Daily Runs every day. Use the Time field to specify the time of day.
    Weekly Runs on one designated day of each week. Use the Time field to specify the time of day.
    Monthly Runs on one designated day of each month. Use the Day field to select the day of the month. Use the Time field to specify the time of day. If the designated day does not occur in the month, the schedule does not run that month. For example, if you designate day 30, the schedule does not run in February.
    Periodically Runs every designated period of time. Use the Repeat Interval field to define the period of time in days, hours, minutes, and seconds. The first Discovery runs at the point in time defined in the Starting field. The subsequent discoveries run after each Repeat Interval period passes.
    Once Run one time as designated by the date and time defined in the Starting field.
    Weekdays Runs every Monday, Tuesday, Wednesday, Thursday, and Friday. Use the Time field to select the time of day.
    Weekends Runs every Saturday and Sunday. Use the Time field to select the time of day.
    Month Last Day Run the last day of every month. Use the Time field to select the time of day.
    Calendar Quarter End Runs on March 31, June 30, September 30, and December 31. Use the Time field to select the time of day. To change the dates, modify the DiscoveryScheduleRunType script include.
    After Discovery Allows you to sequentially stagger the schedule. Use this option to run this schedule after the Discovery designated in the Run after field finishes. Select the Even if canceled check box to designate that this discovery should run even if the Run after Discovery is canceled before it finishes.
    • This option is not valid when the Discovery is started via DiscoverNow, or when using the Discover CI feature.
    • You cannot designate an inactive Discovery schedule.
    • You cannot create a loop by designating the run after Discovery to be the same Discovery.
    • This Discovery does not run if the Run after Discovery does not finish, with the exception that the Even if canceled check box is selected and the Discovery is canceled.
  8. Click Submit.
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