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Conflict Detection

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In this lesson, you will learn:

  • What conflict detection checks
  • The kinds of conflict
  • How to read the Conflicts list
  • How to test and fix a conflict

🔁 Quick look back: Last time: Maintenance Windows and Blackout Schedules. You learned how maintenance windows allow changes and blackout schedules block them.

1 Two changes, one server

Two engineers plan work on snwr-vpn-gw-01 for the same night.

  • One is replacing the certificate.
  • The other is updating the software.
  • Neither knows about the other.

🎯 The problem: Clashing changes are a common cause of outages.

👉 The fix: let ServiceNow check every change for conflicts before it’s approved.

2 What it checks

Key term: Conflict detection

ServiceNow checks a change’s planned dates against blackouts, maintenance windows and other changes.

Key term: Conflict status

A field on the change: No conflict, or Conflict.

Conflict Means
Blackout The change is planned during a blackout
Outside maintenance window The change isn’t inside the CI’s maintenance window
Same CI already scheduled Another change touches the same CI at the same time
Conflict detection on CHG0030045. Planned for Thursday 22:00, during the quarter-end freeze. Conflicts found: blackout, SNWR Quarter-end freeze; outside the maintenance window of snwr-vpn-gw-01; and the same CI is already scheduled by CHG0030051 for a software update. Fix: move to Sunday 02:00 in the next maintenance window after the freeze, and agree an order with the other change.
Figure 1. Three conflicts found before anything broke.

3 Fixing a conflict

  1. Read each conflict in the Conflicts list.
  2. Move the change to the next maintenance window after the freeze.
  3. Talk to the owner of the other change, and agree an order.
  4. Run the conflict check again. It should say No conflict.

💡 Good to know: Check conflicts before sending a change for approval. CAB doesn’t want to see changes with open conflicts.

4 Let’s try it: test a conflict

  1. Open a normal change on the CI with the Sunday maintenance window.
  2. Set the planned dates inside your quarter-end freeze. Save.
  3. Use Check Conflicts. Read the Conflicts related list.
  4. Move the dates to Sunday 02:00 to 04:00 after the freeze. Check again.
  5. Check the conflict status is now No conflict.

5 Quick recap

  • Conflict detection checks dates against blackouts, windows and other changes
  • Three conflicts: blackout, outside window, same CI
  • Read the Conflicts list and fix each one
  • Move to the next window and agree an order
  • Check conflicts before approval

6 Check yourself

Think of your answer first. Then tap to check.

1 Name the three kinds of conflict. Show answer

Blackout, outside the maintenance window, and the same CI already scheduled.

2 Where do you see the reasons for a conflict? Show answer

In the Conflicts related list on the change.

3 How did SNWR fix CHG0030045’s conflicts? Show answer

Moved it to the next Sunday window after the freeze, and agreed an order with the other change.

4 When should conflicts be checked? Show answer

Before the change goes for approval.

Nice work! You tested conflict detection. 🎉
Next up: The Change Schedule

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