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Impact Analysis for Changes

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In this lesson, you will learn:

  • What impact analysis is
  • How a dependency map shows impact
  • How to fill impacted services
  • How to test it on CHG0030045

🔁 Quick look back: Last time: Support Groups and CI Ownership. You learned how a CI’s support group routes incidents and who owns the CI’s data.

1 “Nobody told us!”

Last year, a network change broke email for London.

  • The change named one router.
  • Nobody knew email ran through it.
  • Arjun found out from angry users.

🎯 The problem: If you can’t see what depends on a CI, changes break things by surprise.

👉 The fix: check the CI’s dependency map, and list impacted services before CAB.

2 The dependency map

Key term: Dependency map

A picture of a CI and everything connected to it, upstream and downstream.

Key term: Impact analysis

Working out what a change could affect, before you make it.

Impact of CHG0030045 on snwr-vpn-gw-01. The gateway supports the offering SNWR Network - VPN, part of the service SNWR Network. Remote staff use VPN to reach SNWR Email on snwr-mail-01 and snwr-mail-02. Impacted services: SNWR Network, and SNWR Email for remote users. A note says Arjun is told before CAB.
Figure 1. One gateway. Two services affected.

3 How impact reaches the change

  1. Set the CI on the change.
  2. Use Refresh Impacted Services on the change.
  3. Check the list. Add anything missing.
  4. Tell each service owner before CAB.

⚠️ Heads up: The map is only as good as the relationships in the CMDB. If a link is missing, the impact will be missed too.

💡 Good to know: Need a refresher? See Fundamentals › CMDB Essentials › CI Classes & Relationships.

4 Let’s try it: test impact on CHG0030045

  1. Open CI snwr-vpn-gw-01. Open its dependency view (the map icon or Dependency Views).
  2. Check what it connects to. Add a relationship to SNWR Network – VPN if it’s missing.
  3. Open CHG0030045. Make sure the CI is snwr-vpn-gw-01.
  4. Use Refresh Impacted Services. Check SNWR Network shows in Impacted Services.
  5. Add a work note: “Arjun told about VPN impact on remote email”.

5 Quick recap

  • Impact analysis finds what a change could affect
  • The dependency map shows what’s connected to a CI
  • Refresh Impacted Services fills the list on the change
  • Missing relationships mean missed impact
  • Tell service owners before CAB

6 Check yourself

Think of your answer first. Then tap to check.

1 What does a dependency map show? Show answer

A CI and everything connected to it.

2 How do impacted services get onto the change? Show answer

Use Refresh Impacted Services, then check the list.

3 Why might the map miss a service? Show answer

A relationship is missing in the CMDB.

4 When should Arjun hear about the VPN change? Show answer

Before CAB.

Nice work! You tested impact analysis on a real change. 🎉
Next up: Predictive Intelligence for Categorization and Assignment

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