A step-by-step playbook for migrating from legacy ITSM platforms to ServiceNow, with sample data-mapping templates and a parallel-run strategy.
May 9, 2026·2 min read·By admin
At a glance
Topics
Implementation Services · Servicenow
Published
May 2026
Migrating from a legacy ITSM platform to ServiceNow is one of the most common — and most over-scoped — programs we see. This 26-page playbook documents Mergen’s reference approach across the three most common source platforms: BMC Remedy, Cherwell (now Ivanti), and Jira Service Management.
What the playbook covers
Discovery checklist — what to inventory before sizing the migration (custom fields, integrations, automation rules, historical data scope)
Data-mapping templates — proven field mappings from each source platform to ServiceNow tables, with notes on common gotchas
Customization triage — how to decide which legacy customizations to rebuild, which to drop, and which to leave for later
Cutover models — big-bang vs parallel-run vs phased: when each is appropriate
Historical data strategy — how much history to migrate (with cost / value tradeoffs at each tier)
Decommission plan templates — practical scripts for ramping down the source platform
Risk register — the 14 risks we always carry into a migration program, with mitigation patterns for each
Real-world references
The playbook includes anonymized references from migrations we’ve led, including:
A tier-1 bank that consolidated 11 legacy ITSM tools onto a single ServiceNow instance
A global manufacturer that migrated 40,000 historical incidents from BMC Remedy
A government agency that migrated from Cherwell with FISMA continuity requirements
Whether you're modernizing an existing platform, implementing new capabilities, or exploring AI-driven transformation, Mergen's certified experts will help define the right roadmap, scope, and delivery approach for your business.