What is incremental migration?
Also known as
Definition
A migration rarely happens in one pass. The initial migration moves the bulk of the content, but users keep working in the source environment while the target is being set up and validated. Files get updated. Emails arrive. Teams conversations continue. By the time you're ready to cut over, the destination is already out of date.
That's what incremental migration solves. After the initial pass, delta runs copy only what's changed: new files, updated documents, new Teams messages. Each run brings the destination closer to the current state of the source. The closer they are at the moment of cutover, the shorter the cutover window and the less disruption for users.
tip
Schedule incremental runs overnight. The less you move on cutover day, the lower the risk. Running incremental passes on a schedule in the weeks before cutover keeps the destination current without IT having to trigger each one manually.
Why it matters
Users keep working while migrations run. Incremental migration is what keeps the destination from falling further behind.
- Shorter cutover windows: A shorter cutover window means less disruption and a smaller risk of something going wrong under time pressure.
- Validation & testing: Incremental runs give migration teams a chance to validate that content is landing correctly at the destination before the final cutover.
- Business continuity: Users stay productive in the source environment while the migration runs in the background. Incremental runs keep the destination current so users don't lose work when they switch over.
Commonly confused with: Full synchronization
Full sync keeps two environments in continuous alignment, including deletions. Incremental migration is not full sync. It copies new and updated content, but it doesn’t delete content at the destination that was removed at the source. It’s a planned, time-limited process with a defined cutover at the end.
What we see out there
Incremental runs don't replace cutover planning.
IT teams run incremental passes right up to the cutover date and are still surprised by how much planning the final transition takes. Business validation, change freeze decisions, and user communication don't happen automatically. They need to be planned separately.
Frequently asked questions
What changes are included in an incremental run?
New files and updated documents that are newer at the source than at the destination. For Teams, incremental copy also picks up new conversation messages and replies, new apps and tabs, updated team and channel settings, team membership changes, and Planner updates. Content deleted at the source is not deleted at the destination. You'll need to handle those manually after cutover.
How many incremental runs do we need?
It depends on how active the source environment is and how long your migration takes. The goal is to get the destination close enough to the source that the final cutover window is short. For large or active environments, running incremental passes on a schedule (daily or overnight) in the weeks before cutover is common. The final run should happen as close to the cutover moment as possible, ideally after a change freeze.
What happens to deleted content?
Incremental migration doesn’t delete content at the destination that was deleted at the source. It actually avoids accidental data loss during the migration process. If you need the destination to reflect deletions from the source, you'll need to handle those manually after the migration is complete.
Does incremental migration include permissions?
For SharePoint and OneDrive content, permissions are handled based on your copy options and aren’t automatically re-synced on each incremental pass. For Teams, membership changes (including private channels) are picked up during incremental copy. Permissions that changed at the item or library level between runs may need to be verified after the final pass. Check your migration report after each run to catch any permission-related warnings.
