How are you uniquely identifying CIs in your environment today?

Suggy · ‎06-05-2024

I always thought Serial number field could be used to uniquely identify a CI in the CMDB.

Even OOB Hardware identifier uses 'Serial number' in identifier entries.

I was stumbled upon seeing this official article which says Serial number should not be considered as UNIQUE, and ServiceNow only giving OOB identifiers with Serial number as unique.

The article at the end says use IRE rather than setting the serial number as unique.

Also we know that name can be duplicated, same with IP address, MAC address etc.

Then what on earth should we consider as unique to identify a CI? 😮

Please do let me know what you have considered as unique in your CMDB projects.

Thanks in advance!!!!

richardbrounste · ‎06-06-2024

While Serial number might technically be possible to be duplicated between servers and operating systems from different manufacturers, they are still a good mechanism for unique identification.

1. Serial numbers will not change once assigned. IP Addresses and MAC Addresses (on virtual hardware) can change, which is why they are not reliable for unique identification. Serial numbers don't change.

2. While it is theoretically possible that the serial number in a Linux OS to be the same as the serial number in a Windows OS or some other system, it is highly, highly, highly unlikely. The odds are astronomical. So, you should consider that these serial numbers are unique.

That's all that's needed for a unique identifier. You should feel safe with the serial number as long as the serial number can be queried....whether on Earth or any other planet.

View solution in original post

Ashok Sasidhara · ‎06-07-2024

While Serial Number is the most suitable identifier for many types of hardware devices, it is recommended to use a combination of attributes specified in the identification rules of each CI class to reduce the possibility of duplication. So it is very important to ensure that all CMDB data population methods go through the IRE. In the following article, I have explained about the IRE in detail:

https://servicenowguru.com/cmdb/servicenow-cmdb-identification-and-reconciliation-engine-ire/