Microsoft 365 Tenant to Tenant Migration Overview


The current economic climate is ripe for mergers and acquisitions to become more common around the globe. Tenant to tenant migrations typically have a large business impact and will likely include significant downtime for every transitioning user, a lot of manpower from IT team members, and there will be some data that cannot be transitioned to the target tenant. However, M&A isn’t the only reason a customer would consider a migration of this kind. Some companies may choose to rebrand which could require a change to their domain which would also in turn, require a tenant migration.

What is a tenant?

A tenant is the set of services assigned to an organization. The most common approach used to assist clients during mergers & acquisitions is a tenant-to-tenant migration. Larger organizations could consider a multi-tenant environment but are extremely uncommon and are typically reserved for organizations with a significant user count.

What happens in a tenant-to-tenant migration? 

Tenant-to-tenant migration steps focus on moving user accounts, shared resources and data between two M365 tenants. Tenant migrations are typically broken down into phases that will eventually lead to migrating users being fully operational in the target tenant:

  • Target tenant preparation
  • Data prestaging migration
  • Cutover
  • Day 1 support
  • Source tenant cleanup

Most of the user-impacting tasks and business interruptions will happen during the cutover phase.  Careful planning and clear business requirements can go a long way to limiting the impact on the business.

The more you know –

  • 65% of Microsoft 365 groups have a team attached
  • 25% of Microsoft 365 groups are inactive and 7% have no valid owner
  • On average- 5,406 items in SharePoint Online have unique permissions which means there may be a lot of potentially broken permissions

The following are things to consider when preparing for a tenant consolidation/merger:

  • Make sure both tenants are organized, current, and in a healthy state as part of the pre-migration planning
    • Perform an audit/detailed inventory of the existing state - ensure environment is configured to best practice
      • Do you know where all of the information (amount/type) is stored?
      • Who has access to that content?
      • Do you know the hierarchy of those data repositories?
      • Do you know their sizes?
      • Is the data actually being used?
      • What workloads are being used?
      • What actions might you need to run on certain items?
    • Perform a clean-up of the existing state – users and data that you no longer have a need for can have a burdensome effect on a migration, both from a timing and cost perspective. Identify and fix potential issues ahead of time to ensure a successful tenant to tenant migration. Here is a list of some things to look out for:
      • URLs
      • File sizes
      • Character limitations
      • Custom solutions
      • Branding
      • InfoPath
      • Workflow state and history
      • Permissions (do you have access to all the files?)
      • Folder with more than 5000 items
      • Unsupported site templates
      • Orphaned users
      • Checkout out files
      • Unsupported list templates
      • File extensions
    • Teams is used now more than ever – understand the relationship between Teams, SharePoint Online, and OneDrive for Business and what impact each service has on your environment
      • SharePoint team site – files and folders stored in the team document library or shared in a channel, external emails sent to the team, the team’s wiki page, and each channel’s OneNote assets
      • Exchange team mailbox – group chat and channel chat conversation history, team mail, and contacts
      • Exchange mailboxes of individual users – private chat conversation history, voicemails, and calendar meetings
      • OneDrive for Business of individual users – files attached to private chat sessions, or a stored chat during a meeting or call, are uploaded and stored in the OneDrive account of the user who shared the files
      • OneDrive organizational document library – users personal OneNote’s
      • Azure Blob Storage – images and media (except GIFs) shared in chats
      • Stream – meeting recordings
      • Permissions

Do you need to migrate everything in Microsoft 365 from tenant to tenant? No problem, we are happy to schedule a consultation.

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