CMDB Identification rules explained - Support and Troubleshooting

CMDB Identification rules explained Summary .ns-kb-css-body-editor-container { p { font-size: 12pt; font-family: Lato; color: var(--now-color--text-primary, #000000); } span { font-size: 12pt; font-family: Lato; color: var(--now-color--text-primary, #000000); } h2 { font-size: 24pt; font-family: Lato; color: var(--now-color--text-primary, black); } h3 { font-size: 18pt; font-family: Lato; color: var(--now-color--text-primary, black); } h4 { font-size: 14pt; font-family: Lato; color: var(--now-color--text-primary, black); } a { font-size: 12pt; font-family: Lato; color: var(--now-color--link-primary, #00718F); } a:hover { font-size: 12pt; color: var(--now-color--link-primary, #024F69); } a:target { font-size: 12pt; color: var(--now-color--link-primary, #032D42); } a:visited { font-size: 12pt; color: var(--now-color--link-primary, #00718f); } ul { font-size: 12pt; font-family: Lato; } li { font-size: 12pt; font-family: Lato; } img { display: ; max-width: ; width: ; height: ; } } Data flow into CMDB overview : There are multiple ways that a data can be pushed into CMDB like SCCM, SQL, Excels, Discovery, Import sets etc. Import set is a functionality using which we can connect to customer's DB to pull the data and push it to CMDB.

Use Case Scenario :

Suppose some data related to a particular CI (Configuration Item) is pushed to CMDB from five data sources with same Name and Serial number. In this scenario five different records with same data are created in the CMDB. There arises a confusion to choose among the five records, for any maintenance activity. This is a best example for data duplication as there is no active mechanism during the record insertion into CMDB.

IRE (Identification and Reconciliation) :

IRE is a mechanism which identifies, performs the appropriate action and acts as a gateway between the datasource and CMDB. IRE has two modules within

Identification : This is the mechanism of choosing which record to insert and which to update in the CMDB. Reconciliation : This involves choosing the trusted data sources from where the data has to be accepted into CMDB.

Identification rules : Set of rules with certain attributes like Serial Number, Name, Serial Number Type etc based on which data is pushed into CMDB. ServiceNow Out Of The Box provides certain identifier rules by default and the user has an option to create new rules. These list of rules can be viewed under the instance in Class Manager, which is the repository of all the classes in CMDB. Configuration Item (cmdb_ci) is the parent class to each and every class in CMDB. The CMDB classes have a set of their own unique Identifiers or they can inherit it from parent class as well. Each Identifier entry should have

Priority assigned to it. The priorities are set as 100, 200, 300.. in a sequence, out of which 100 being the top most priority. Table on which it has to search Value to search

How the Identification rules work in the real time scenario : When a device is Discovered, the data is pushed to the IRE engine where it goes through all the set of defined Identification rules. If any one of the rules passes, the data is updated with respect to that particular CI on the corresponding table. Else if no rule is passed, a new record is created/inserted into CMDB. Related Links .ns-kb-css-body-editor-container { p { font-size: 12pt; font-family: Lato; color: var(--now-color--text-primary, #000000); } span { font-size: 12pt; font-family: Lato; color: var(--now-color--text-primary, #000000); } h2 { font-size: 24pt; font-family: Lato; color: var(--now-color--text-primary, black); } h3 { font-size: 18pt; font-family: Lato; color: var(--now-color--text-primary, black); } h4 { font-size: 14pt; font-family: Lato; color: var(--now-color--text-primary, black); } a { font-size: 12pt; font-family: Lato; color: var(--now-color--link-primary, #00718F); } a:hover { font-size: 12pt; color: var(--now-color--link-primary, #024F69); } a:target { font-size: 12pt; color: var(--now-color--link-primary, #032D42); } a:visited { font-size: 12pt; color: var(--now-color--link-primary, #00718f); } ul { font-size: 12pt; font-family: Lato; } li { font-size: 12pt; font-family: Lato; } img { display: ; max-width: ; width: ; height: ; } } The identification rules be it Out Of Box or customised, always matches the data with "equals" case but not matches with any other search parameters like "starts with", "reg expression", "contains" etc. When a particular Identification rule is skipped during Discovery, that could be a scenario when the payload does not contain the data related to a specific attribute defined on that rule.