Basically, a CMDB consists of:

Each configuration item has a defined schema.

Configuration Item Class: Each configuration item must be associated with a class, which defines its properties.
Relationship class: Defines the type of relation between configuration items.

You can extend both the classes to add additional properties or customize the properties.

ServiceNow supports application service, which is a set of interconnected applications and hosts that offer a service. ServiceNow allows you to create an application service manually, by using an API, or can automatically discover by Service Mapping. All these applications are stored in ServiceNow CMDB.

When you add a ServiceNow datasource into

VMware Aria Operations for Networks

,

VMware Aria Operations for Networks

fetches the configurations items and the relationships from the ServiceNow CMDB configuration file.

VMware Aria Operations for Networks

fetches data in regular intervals, by default.

The complete data fetch happens every 12 hours, which fetches all the records of the classes defined the CMDB configuration. Also, the complete fetch happens when you add or update the datasource.
The delta fetch happens every 2 minutes, which fetches all new, modified, and deleted records of the classes defined in the CMDB configuration. Approximately,
VMware Aria Operations for Networks
takes around 12 minutes to reflect these details on the user interface.

VMware Aria Operations for Networks

fetches the class hierarchy and the relationship types during complete fetch only.

Default values for Limitations

Limit Name	Description	Default Value	Impact for Exceeding the Limit
maxAppsPerDataSource	Maximum applications per datasource.	5000	The data source stops fetching data with an error on datasource and alerts page and the applications are not updated.
maxTiersPerApp	Maximum tiers that can be stored per application.	150	The applications are not updated until number of tiers are reduced to fit in limit.
maxMembersPerApp	Maximum members that can be stored per application.	5000	The applications are not updated until number of members are reduced to fit in limit.
maxGraphTraversalStackSize	Maximum size of stack used in graph traversal.	10000	The application will not get created and throws SizeLimitExceededException .
maxResponseAppCount	Maximum apps that can be returned in API response.	5000	Only the number of applications that fits the limit are returned and UI shows error.