Issue
Symptoms
After creating Identification Inclusion Rules for a CI Class and running Discovery, duplicate CIs are created.
Release
Any where Identification Inclusion Rules can be created.
Cause
Identification inclusion rule doesn't prevent records to be added into be CMDB. Instead, based on Inclusion rule, CI gets added or updated into CMDB during the identification process. Generally, inclusion rules shouldn't be created based on criterion attribute as this can lead to the creation of duplicate CIs.
Resolution
The example below illustrates how creation of Identification Inclusion Rules can lead to duplicate CIs:
For example you are creating an identification rule on windows server:
1. You have 'name' as one of your criterion attributes
2. Also, in the identifier inclusion rule, you add a condition where OS Version = 'Linux'
Now you run the discovery on Windows server name = WS1 and OS Version ='Windows'
So, IRE will look for Name matching and check if OS Version='Linux' is already in CMDB. In this case, its not true and it will create a record with WS1 where OS version = "Windows"
Now, you run the same discovery and , IRE will look for Name matching and check if OS Version='Linux' is already in CMDB. In this case, its not true and it will create another record with WS1 where OS version = "Windows" (now you have 2 entries)
But if you run the discovery with same but OS Version ='Linux' and IRE will look for Name matching and check if OS Version='Linux' is already in CMDB. In this case, its not true and it will create a record with WS1 where OS version = "Linux" (now you have 3 entries)
You run the last run discovery with same and OS Version ='Linux' and IRE will look for Name matching and check if OS Version='Linux' is already in CMDB. In this case, yes it is there and it will simply update the record ( you still have 3 entries)
Hence: So, Inclusion rule does the matching and update only which are matched otherwise insert every time you run the discovery.
In Summary:
- Inclusion rule doesn't prevent records to be added into be CMDB
- Don't create identification inclusion rule on criterion attributes
- Wrongly created inclusion rule can cause duplicates.
- Additional Information