Data Sync vs Data Migration: Two Very Different Problems That Look the Same

Business owners often use “sync” and “migration” interchangeably. “We need to sync our data to the new system” or “We need to migrate the data across and keep it updated.” The words get swapped — until a project gets scoped wrong because everyone assumed a different meaning.

Data sync and data migration are fundamentally different operations. Understanding the distinction is the first step to getting either one right.

What’s the Difference?

Data migration is a one-time move. You take data from System A and transfer it to System B. Once done, System A might be decommissioned or archived. Think of it like moving house — you pack up, transport everything, and live at the new address.

Data sync is an ongoing process. Both systems stay active, and data needs to stay consistent between them continuously. Think of it like having two offices — files and records need to match at all times.

When You Need Migration

Replacing a system. Moving from an old CRM to a new one, from spreadsheets to a database, from MYOB to Xero. You need historical data transferred to the new platform.

Consolidating systems. Two departments running separate tools that do the same thing. You’re merging into one, and the data needs to move once, be cleaned, and de-duplicated.

Platform upgrades. A vendor releases a new version with an incompatible data format. Your data needs extraction, transformation, and loading into the upgraded platform.

When You Need Sync

Running parallel systems. Your CRM and accounting software both need customer data. Your e-commerce platform and warehouse both need inventory levels. These systems serve different purposes — both stay active.

Real-time operational needs. A sale on Shopify needs to reduce stock immediately. A payment in Xero needs to update your CRM today, not next week.

Multi-channel or multi-location. Every channel or location needs current, consistent data.

The Technical Differences

Migration: Extract, Transform, Load

Data migration follows an ETL pattern. You pull data out of the source, reshape it for the destination, and load it in.

Key considerations:

• Data mapping — every source field needs a destination. Some map directly, some need transformation, some have no equivalent.
• Data cleaning — migration is your chance to fix years of duplicates, inconsistent formatting, and incomplete entries. Clean it now or carry the mess forward.
• Referential integrity — records that reference other records (invoices referencing customers, jobs referencing sites) must maintain those relationships. IDs change between systems, so the migration needs to remap every reference.
• Volume — migrating 500 records is trivial. Migrating 500,000 with complex relationships can take days.

Sync: Ongoing Conflict Resolution

Data sync is technically harder because it never ends. You’re building a process that must handle every scenario your business encounters, permanently.

Key considerations:

• Direction — one-way (System A pushes to B) or two-way (changes flow both directions)? One-way is dramatically simpler.
• Conflict handling — when the same record is updated in both systems, which version wins? Do you merge, pick the most recent, or flag for manual review?
• Timing — real-time via webhooks, near-real-time via polling, or daily batch? Tighter timing means more complexity and cost.
• Failure recovery — does the sync retry on failure? Does it queue records? Does it alert someone? A sync that silently drops records is worse than no sync at all.

The Mistakes People Make

Treating Migration Like Sync

“We’ll migrate the data and then keep it syncing.” That describes two separate projects with different tools, testing, and budgets. Lumping them together leads to projects that do neither well.

Syncing When They Should Migrate

Syncing your old CRM to your new CRM because “some people still use the old one” just delays the inevitable. Complete the migration, decommission the old system, and stop doubling your data quality problems.

Migrating When They Should Sync

Exporting a CSV from System A every Friday and importing it into System B isn’t migration or sync — it’s manual data entry with extra steps, creating a week of lag and risking duplicates.

Underestimating Data Cleaning

Dirty data is the enemy of both approaches. The difference is timing: migration gives you a window to clean. Sync requires clean data from the start, because every dirty record contaminates the other system automatically.

Making the Decision

Ask these questions:

1. Are both systems staying active? If one is being retired, you need migration. If both stay, you probably need sync (and possibly an initial migration to align them).
2. How often does the data change? Rarely changing data can be migrated periodically. Frequently changing operational data needs sync.
3. What’s the cost of stale data? If outdated data causes real problems (overselling, incorrect invoices), you need sync. If a day of lag is acceptable, batch import might suffice.
4. What’s your data quality today? Poor quality makes sync especially dangerous — dirty data propagates to every connected system automatically.
5. What’s your budget for ongoing maintenance? Migration is a project with an end date. Sync is infrastructure that needs permanent monitoring.

Most growing businesses eventually need both: a migration when adopting a new system, and ongoing sync to keep active systems connected. The key is recognising which problem you’re solving right now.