Dependent CI Cleanup or stop discovery

[Balaji Chandras]

Hi Team,

We could see around 6000 to 7000 CIs getting created every after discovery and most of them dependent Cis like Switch forwarding rule, Switch port, Router interface IP Address, Hardware type, etc., and it's causing our ServiceNow getting slow.

We would like to understand how these dependent CI will be getting created (If there is any diagram or flow would be great helpful) and what is the best practice to cleanup these CIs and keep CMDB accurate one.

Thanks in Advance!

[CMDB Whisperer]

First, I would question the assumption that this is causing slowness.  While certainly the size of your ServiceNow database can impact its performance, a few thousand CIs generally isn't going to make a difference.  If you are experiencing slowness there is more to consider around the reasons for this, and the line of questioning is worth pursuing further before making assumptions that reducing the size of the CMDB by a few thousand CIs is going to help you.  It is typical for a CMDB to contain hundreds of thousands to millions or more CIs, without issue, so it's likely not going to be worth the effort and functionality tradeoffs.  

Switch ports are generally not very useful and can be extremely large.  There are ways to filter out when they get created so you won't accumulate so many, and you can probably "clean these up" without impacting too much.  But Switches and Routers and their related configuration items are worth keeping.  They represent important information about the network configuration of these devices, and they will be kept up to date with each discovery scan.  They provide information that can be used to trace network routes, so you would be well advised to continue discovering them.  

If you find that they are causing you issues with the user experience, you should look into questions like these:

• Do I have the right navigator modules configured so that users are selecting CIs based on what they need?
• Which CI classes are marked as Principal CI Classes in my CI Class Manager?
• Are the reference qualifiers for tables such as Incidents and Change Requests filtering in only the Principal CI classes to be selected by users?

That said, you can configure at a very high level which types of devices your Discovery scans are going to discover, so by all means make sure this is configured for the kinds of devices you intend to manage in your CMDB.  And beyond that, if you are experiencing slowness you can contact ServiceNow support to do a health scan on your instance to see if there are any underlying issues or recommended actions for improving performance.

[Balaji Chandras]

Thanks for the information.

If you could share any diagram that how the IP Address, Switch forwarding rule, Switchport, Hardware type Class CIs are getting created.

Customer wants to understand the discovery and importance of these Class Cls and expecting the documentation about the discovery, purpose, impact and then the best practices to clean-up those Class Cls.