About discovery phases

[newhand]

Hi everyone!

I am learning about discovery, and I know there are four phases during the discovery process: Scanning, Classification, Identification, and Exploration.

I understand what each phase does, but I can't understand why the Identification phase runs before the Exploration phase.

By running the Exploration phase, we can gather more information about the CI (Configuration Item), and these information may be used by the Identification phase.

Therefore, I think the Exploration phase should run before the Identification phase.

Can someone tell me why?

Thanks!

[pratiksha5]

↑During the Identification phases, is there already enough information for IRE to check if the given CI is already present in the CMDB or not?

In the identification phase, discovery does not match all the attributes. It matches only which are mentioned in the identification reconciliation engine. For example, for a Windows server, if the IRE rule defined serial number and serial number type as ID attributes then it will just try to see if any incoming data have the same serial number and serial number type. If the match is found then it will update the CI. If not found then a new CI will be created. 

[newhand]

@pratiksha5 

Thank you for your explanation。

Identification rule can be created or modified by users.
If a attribue populated in the Exploration phase is used in the Identification rule ..what will happen when the IRE runs....I think when IRE runs, the attribue was blank..then the result will be out of expected

For example: 

Assume Discovery can find 5 attributes （A，B，C，D，E）

 A and B are populated in the Scanning or Classification phase ,

C,D,E are populated in the Exploration phase.

 Therefor , when creating the Identification rules, we should only use A and B,because CDE have not be populated when IRE runs.

Now , the problem is where we can know what we can use in the Identification  rule?

and why not run the Exploration phase before Identification  phase (if so ,we can use A~E in the Identification  rules)?

This is my confusion。

[pratiksha5]

Assume Discovery can find 5 attributes （A，B，C，D，E）

 A and B are populated in the Scanning or Classification phase ,

C,D,E are populated in the Exploration phase.

 Therefor , when creating the Identification rules, we should only use A and B,because CDE have not been populated when IRE runs.

Discovery doesn't populate anything in the first two phases in CMDB.

In identification, it will get the few details of the CI which get checked against the IRE. If any of the attributes matched with any existing CI then it updates it. 

Please check the link to understand more : https://docs.servicenow.com/en-US/bundle/utah-it-operations-management/page/product/discovery/concep...

I would highly recommend checking some patterns to understand what is done in each phase. 

Mark my answer helpful if it helped. 

Best of luck

Pratiksha

[newhand]

@pratiksha5 
Thank you for you replay.

I will have a futher study !

[newhand]

@pratiksha5 
I guesss ，before identification phase，discovery may have got enouth information for IRE。
While in the Exploration phase，discovery will get more informations that can not used in the identification rules(such as installed soft, running process... nobody will use thses information for identification  rule..)