This information applies to both the Confluence Cloud Migration Assistant and Jira Cloud Migration Assistant. This does not apply to other server to cloud migration strategies.
How user migration works
The migration assistants use email addresses as the key identifier for your users. The first time you migrate, the Migration Assistant will copy all the users from your server and create Atlassian Accounts for them in cloud using their email addresses. These users will only be added to your cloud license if they are a member of a group with license permissions.
Every migration, after the first, the Migration Assistant will link space or project data to the existing email addresses in cloud rather than recreating those users. This means that it will be much faster to migrate users and groups from the second migration onwards. Note: the estimated time to migrate does not take this into account.
Recommendations for large userbases
If you have a large userbase, we recommend migrating all your users and groups without any spaces or projects first. This can happen while your users are still working in server, as no space or project data will be extracted (meaning no downtime). Then, when you come to migrate spaces or projects later, it will be a faster migration with a shorter downtime.
If you're using the Jira Cloud Migration Assistant you can also choose to migrate only the users referenced in the projects you are migrating. This can reduce the number of users you need to migrate and will mean a shorter downtime. Learn more about migrating users and groups with the Jira Cloud Migration Assistant.
Make sure you read our guidance on user migration strategies before migrating any users to cloud.
More information and support
We have a number of channels available to help you with your migration.
For more migration planning information and FAQs, visit the Atlassian Cloud Migration Center.
Have a technical issue or need more support with strategy and best practices? Get in touch.
Looking for peer advice? Ask the Atlassian Community.
Want expert guidance? Work with an Atlassian Partner.