ServiceNow Security, Performance, and Best Practices – ACLs, Instance Health, and Maintenance

Learn ServiceNow security, performance, and best practices. Understand ACL rules, data security, instance health, update sets, debugging, and logs with practical examples for admins and developers

Security and Access Control

ACL Rules

Access Control Lists (ACLs) define who can access what in ServiceNow.

Key points:

  1. Can be applied at table, field, or record level
  2. Can control create, read, write, delete operations
  3. Conditions and scripts can restrict access dynamically

Example:

  1. Only users with “itil” role can update incident priority
  2. HR fields visible only to HR group

Data Security Best Practices

  1. Apply the principle of least privilege (give minimum required access)
  2. Use roles instead of direct user permissions
  3. Audit sensitive tables and fields regularly
  4. Monitor and review ACLs for unused rules
  5. Use encryption for sensitive fields

Hands-On: Create ACL Rule

  1. Navigate to System Security → Access Control (ACL)
  2. Click New
  3. Select Table or Field
  4. Define Operation (Read, Write, Create)
  5. Add Condition or Script
  6. Assign roles
  7. Save and test with a user account

Performance and Maintenance

Instance Health

Monitoring instance health ensures smooth performance.

Key metrics:

  1. Memory and CPU usage
  2. Scheduled jobs
  3. Background scripts
  4. Database size and growth

ServiceNow provides dashboards and Instance Health reports for monitoring.

Update Sets

Update Sets track configuration changes across instances.

Key points:

  1. Capture all configuration and customization changes
  2. Move updates from Development → Test → Production
  3. Avoid conflicts by keeping separate update sets for different tasks

Best practices:

  1. Commit frequently
  2. Avoid direct changes in production
  3. Use meaningful update set names

Debugging and Logs

Logs help identify and resolve errors.

Key logging tools:

  1. System Logs → Errors, Warnings, Transactions
  2. Script Debugger
  3. Browser console (for client-side scripts)
  4. Flow Designer execution logs

Hands-On: Monitor Performance and Update Sets

  1. Navigate to System Diagnostics → Stats or Instance Health
  2. Review metrics and performance issues
  3. Navigate to System Update Sets → Local Update Sets
  4. Create a new Update Set for your configuration
  5. Test committing changes and moving to another instance

Hands-On: Debug Scripts

  1. Open a Business Rule, Client Script, or Flow
  2. Enable debugging
  3. Trigger the script and review logs
  4. Fix errors based on log information

Completion Outcome

After completing this chapter, you will be able to:

  1. Create and manage ACLs for secure access
  2. Apply data security best practices
  3. Monitor instance health and performance
  4. Use Update Sets for configuration migration
  5. Debug scripts and workflows efficiently
  6. Maintain a stable, secure, and well-performing ServiceNow instance