Migration Preparation Tasks

I'm looking at a cutover migration for a relatively small network (< 50 users). I've seen a relatively good guide here, however I seem to remember that there's a lot of preparation tasks that need to take place before you can actually perform mailbox migrations themselves.

For example, I understand that you have to make adjustments to AD so that it's a routeable domain (not .local) and adjust UPN names. Is there a definitive list of preparation tasks which apply to cutover, staged and hybrid deployments?
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Emmanuel AdebayoGlobal Windows Infrastructure Engineer - ConsultantCommented:
The following are the key deployment tasks and events that your carry out in the Prepare phase:

Add and verify your domain name with Office 365. You must add your domain to Office 365 and then create the DNS records to configure your company domain name for use with Office 365 services.

Prepare your on-premises Active Directory for directory synchronization. Successful directory synchronization between your on-premises Active Directory environment directory and Office 365 requires that your on-premises directory objects and attributes are properly prepared.

Enable single sign-on (single sign-on). To enable single sign-on, you must deploy and configure Active Directory Federation Services servers on-premises.

Install the Directory Synchronization Tool and perform synchronization. Directory synchronization enables you to provision user accounts for an Exchange hybrid deployment and simple coexistence, and is mandatory for single sign-on.

Configure email coexistence. You install and configure an Exchange 2010 hybrid server on-premises to enable communication between your existing Exchange servers and Exchange Online.

Configure Lync Online. You optimize your network for Lync conferencing, configuring domain federation and public IM connectivity settings.

Configure SharePoint Online. You prepare for deployment of any custom SharePoint solutions and migration of existing SharePoint content.

Deploy client applications and the Office 365 desktop setup. A hybrid deployment requires that rich client applications are deployed and installed on users’ PCs. The Office 365 desktop setup is deployed to ensure that client applications are properly updated and configured for Office 365.

Perform mailbox size reduction. To improve migration velocity of mailbox content, you may need to reduce the size of user mailboxes.

Prepare customer service desk. Your service desk must be trained to support Office 365 service offerings.

Test and validate email migration and coexistence. Prior to velocity migrations, you set up test user accounts to validate that migration processes and that the Exchange hybrid deployment are functioning properly.

Complete the migration groups and migration schedule. Finalize the groups of users, resources, and shared mailboxes that will be moved at each migration window.


HypervizorAuthor Commented:

However, these don't answer the specifics I mentioned above, e.g. what needs to be done in AD in terms of preparation? What's the easiest way to do this?

There used to be a readiness assessment tool which highlighted all AD accounts and the relevant adjustments required so that they migrate without issue. This tool was superseded by Microsoft OnRamp - however that doesn't seem to be anywhere near comprehensive in this area compared to the assessment tool.

Surely there is a tool or script that would help a) identify and hopefully b) help resolve?
Adam BrownSr Solutions ArchitectCommented:
The answer is it depends. Specifically, are you planning to use Dirsync and ADFS in your deployment or are you planning to have separate credentials for Office365 and AD? The answer to that question will determine a whole lot of what you need to do in preparation. If you don't plan on having Single Sign On, then there isn't really any preparation you need to do in AD. You just need to grant a single mailbox full access rights on all the mailboxes you are migrating and start the migration. If you are using dirsync and ADFS or Dirsync with password Sync, you will need to ensure that the UPN for each user matches what you will be using for login in Office 365, you will also need to do a lot of additional checks. Dirsync and ADFS add a lot of complexity to things both in migration and ongoing management. I've done several Office 365 migrations for clients and I've yet to run into one that goes as planned.

Microsoft has some information available here that you should seriously go through: https://onramp.office365.com/onramp/ there are wizards, tools, and other things that will help you determine how healthy your environment is and get things working properly. If you can, try to find a consulting agency that specializes in Office 365 migrations, as there are a lot of bumps that can completely screw you over if you don't know exactly what you're doing.

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Adam BrownSr Solutions ArchitectCommented:
Also, you don't have to change your domain name. It can be non-public and still work with Office 365. You just need to add a new UPN domain to your forest and assign that to your users (UPN must have a public Domain Name). But this only matters if you want SSO.
HypervizorAuthor Commented:

Many thanks for the info. I didn't realise it wasn't necessary to do any AD work prior to the migration if it was a straight-forward cutover migration. I'd incorrectly assumed that if DirSync required AD users to be a certain way, this was a fundamental requirement for any mailbox migration (I'm still not sure why there would be a difference?).

We'll be doing a cutcover migration, so we won't be using Dirsync and we won't be utilising SSO - so that should make it easier. Did you have any bumps with cutover migrations?
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