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O365 Tenant Migration: Roundtable Q&A

Oct 29, 2020 by Mike Weaver

Two clouds and various workloads, representing the complexities of Office 365 tenant migrations

On behalf of Tony Redmond, Gary Bent, Paul Robichaux, and myself, thank you for attending today’s Expert Roundtable on Office 365 cross-tenant migrations.  

I would also like to thank Tony Redmond (Microsoft MVP and Lead Author of Office 365 for IT Pros) and Gary Bent (Global Infrastructure Architect, Omnicom) for joining us. Their industry experience added lots of practical, real-world advice on a complicated subject matter. 

We covered many questions during the roundtable, but some didn’t make it into the live broadcast. In this post, we will cover as much as we can! 

Questions from the Roundtable 

I am a non-profit with 60,000 accounts and 85 tenants. Where do I begin? 

The first thing you need to do is scope your project. During the session, we talked about the major steps to these migrations: Plan, Move, Manage. 

In the planning stage, you need to discover what your users are using, their activity, and the data volume. This will help you focus your efforts. As a non-profit, you may be quite cost-conscious. In discovery, you may find low use or items that you do not need to migrate. This data will help guide you. The other aspect of discovery is to understand each tenant/organization’s busy/idle periods. Simply asking technical leads, “What is a good time to migrate?” and noting the reason for this answer will help you when scheduling. 

In the webinar, Gary and I talked about how we ordered 137 tenants. All stakeholders came together in a room. We created tenant profile cards that included all major data. We then defined how much could move during a monthly period. Working together as a group, we shuffled the cards around into a base schedule. On the back of the card, we took notes on why we put a tenant on that date, so if we had to shift, we would know if that was the right move. This allowed us to make a tentative schedule and set direction.

This deep-dive discovery of your tenants is crucial, and once you fully understand the make-up, you can start to define each tenant into a ‘T-shirt size’ model of complexity. Once you’ve identified the small, medium, and large tenants based on complexity-level, you can then build a schedule.

When it came to moving, we worked to ensure that the first month was simpler tenants with the idea that we added complexity each week. For example, week one was Exchange only. In week two, we added OneDrive. Week three, SharePoint. Week four, we added Teams. As time went on, we added more complex tenants while addressing the tenants that we simpler. This gave confidence and got processes hardened.

As for manage, you need to handle this a little in your planning stage. Managing a lot of small tenants is different, then managing one large tenant. You likely will need to re-organize staff and reasonability. In the planning stage, you need to address this as the migration activity will take your focus until, one day, you wake up with one large tenant! 

Multi-tenant migrations, especially with more than 10, need a lot of special care. Personally, I find them very interesting, so get in touch! 

How do you handle the aspect of agreeing on a final configuration when combining tenants? 

This really depends on how many tenants and the current state of them. Some organizations have used this opportunity to harden security and restrict the tenant a bit more. You have to be careful not to limit a business unit in doing so, but if you have some tenants that run like the ‘wild west’ and others that operate in a restrictive manner, you will need to reconcile it. 

Data will help you make these planning decisions. You will also need buy-in from the highest levels in your organization. If you have 75 tenants, you should not have 75 Global Administrators. One significant planning aspect is who will hold this access, and admin-level access for sub-services. You all now have to get along in a larger tenant and need more oversight to protect your organization. These situations require a lot of work and can stall some projects for a bit. 

The other major aspect is more tenant migration projects are the result of a Merger, Acquisitions, or Divestiture. Future state, and their roles will drive this as well. There is also the context of is this a small tenant going into a large tenant, a combination of equals, or even a larger tenant going into a smaller tenant. This will drive this decision-making process. 

Regardless, the same three-step process applies… Plan, Move, and Manage. You need to plan for the configuration, move/set the config, and then manage the new tenant going forward. 

How many hours of Project Management time do these projects take? It seems like so much is non-standard. 

There isn’t an easy answer, sadly. The number of tenants you have, the amount of services being used, amount of users, volume of data, activity, and business impacts will all come into play. 

Last week, I completed an Exchange-only project in two weeks from start to finish. I have also worked on multi-tenant projects, and even single-tenant projects that have lasted for over a year. To help, you should learn from past projects, get advice on what other organizations of similar profiles have been through, and make an estimate. 

One thing is clear: The higher quality of the planning and oversight of your project, the less impact there is. Impact and, more importantly, the impact to productivity is hard to calculate. However, when it goes wrong, you can stall many areas of a company. Projects of size need proper planning and oversight to be successful. 

Where should I ‘draw the line’ and just migrate things manually? I only have 30 users. 

If you are 30 users with email, a little bit of OneDrive, and a little bit of SharePoint, you likely can migrate using the Microsoft MRS Preview Program and some manual work. You should ensure you have access to a qualified professional to support you over the weekend and help you as some very complex steps need to occur. You should ensure this professional has tenant to tenant experience. 

I ‘draw the line’ at 50 users. But if you have 30 very complex users, you may have to call in the professionals and Migration Vendors (like Quadrotech!) to help. 

If you have more than 250-500 users, regardless of the complexity, you likely need to use an Office 365 to Office 365 migration tool. 

How do I migrate Microsoft Teams? 

Poor Tony and Paul took this one. There are some very limited APIs that migration vendors like Quadrotech can use. We have had solutions for some time to recreate Teams, their channels, files, and – to some degree – the channel chat. To date, there is no support to migrate Group Chat and 1:1 chat.

Recently, Microsoft released some APIs to support backdating channel chat and impersonating users. There are some limitations, so ensure you get a clear answer from your migration vendor. As of writing this blog, if they claim they move everything, you are not getting a truthful answer. 

Is it possible to transition a domain with mailboxes between tenants without mail flow disruption? 

The short answer is no, but there might be some options. To move the domain, you need to remove all references of the domain, run an ejection process, and then reassign the domain to all the objects. To be in full disclosure here, I would say one in five projects have domain ejection issues, so you want to ensure you have a backup plan and proper support ready should this not go well. 

If you have a third-party mail hygiene product in front of Exchange Online Protection, you might be able to pause mail flow here during the maintenance window. 

Another option is to reduce the TTL of your MX record and put a known down entry in. (You have to change this TTL in advance depending on what your current TTL is!) This will make it look like the mail server is down. The result is that the sender’s mail server will queue the mail for several hours, depending on their configuration (usually up to 48 hours). It would help if you did this with proper advice, but many professionals advocate for this step to prevent NDRs to external senders. 

Do not start your final sync until the domain has been properly imported and addresses assigned. You may find this script helpful as well to collect SMTP address and the Exchange legacy DN: 

Can a tool just be run to analyze the source/target environment and then build what to process?
Yes and no. A tool can be very helpful, but you need to interpret the results. Gary and I talked about this during the roundtable, where they have used our Nova management platform to do this. If you have multiple tenants or even just a complex single-tenant project, this can be a huge help. 

When I am scoping Office 365 tenants for migration, I use Nova to look at what is being used, volumes of data, and activity. This helps me essentially score and assess each tenant. I have a set of reports I like to run, and then I can dig into other reports if I find something suspect. 

You can do some of this with customs scripts. However, a good reporting tool will help you do this a lot faster and allow you to dig into what you find instantly, instead of writing more scripts. Post-migration, this tool can help you manage the now larger tenant. 

If you have multiple tenants, you really should consider a tool like Nova to help you before, during, and after the migration. Although you can do each task with a script, as the service expands and the uses grow, a tool will be able to give you instant data rather than having to constantly update your scripts and processes. Simply click/create a new custom report, and you have what you need. 

What suggestions do you have for the services that do not move like Project, Planner, Microsoft Lists, eDiscovery, and more? 

Sadly, each one of these has different requirements. Some will require manual export and import work from the user (Flow), others will require an administrator to manually recreate aspects (eDiscovery), and some may need to be abandoned (Yammer). 

In the planning phase, this discovery will be very important. This will allow you to help prepare your users for these problematic items. 

Planner, we should note, does have a migration path. There are some great scripts around for this purpose.

I need to split one on-prem system into several systems. Do you have any suggestions?

The first advice is to be very careful. Cross-tenant migrations are complex. You should thoroughly assess if you need multiple tenants as you may find you then have to combine them later. 

With all sorts of policies and features, you can keep business segments fairly-well contained. You should consider getting proper advice on the topic before purposely splitting an on-prem system into several tenants. Sadly, most firms regret doing this. 

Additional Questions 

We got a lot of questions! Some were either a little off-topic, or we didn’t quite have time to go into them. I tried to capture most here.

What role have you seen Organizational Change Management playing in Office 365 Tenant Migrations? 

It can be huge! We developed a great leadership series with Mary Jane Flanigan from MJInspire to help with the People Aspect of this work. Most tenant to tenant migrations are the result of a Merger, Acquisition, or Divestiture. A lot needs to happen! The ‘Method to the MADNess’ series can be found on YouTube.

To close this question out, you may need to get a proper business consultant to help with this aspect. There is an expense to these programs, but it is likely a lot less expensive than the impacts of ignoring these issues. 

Our communication templates are also really popular to help with the technical aspect. These can be found here. 

Do you keep the old tenant or start fresh? What are considerations if the target tenant has a Domain, but you need to keep the source domain on the imported users? 

In the roundtable, Tony and Gary talked about the end state configuration and how to reconcile that. I really would listen to that section as it has some great advice. 

If you want users to keep their SMTP domain branding, you will need to bring the domain over to the new tenant. This requires careful planning and execution.

Microsoft has launched a preview program that enables the ability to route email between tenants to allow for branding to span tenants. This is designed for short-term integration. Users do not need to take on any domains in the target you do not want them to, except for the vanity domain. Ensure you research and get proper support to migrate the domain.

Once you have done it a few times, it is pretty simple, but if you don’t know how to update objects and manage the domain record with your registrar, you should seek help. 

What is the best way to compare Shared Mailboxes in an organization? 

Name collision is a primary concern in a project. Name collision includes names and department shared mailboxes. This needs to be looked for if you are combining tenants.

It is common when a company purchases a smaller company to add an acronym to all shared mailboxes, teams, and SharePoint sites. Think ‘COT-HR’ for the ‘HR’ mailbox if your firm were named Contoso. For name collision, you will need to inform the users coming in that their address is going to shift if you are putting them on the destination domain. 

Pairing down shared mailboxes is also a helpful step. I do this by looking for low activity in most cases. 

In terms of looking for shared mailboxes, this can be done in PowerShell or the Exchange Admin Center. For large and complex projects, I would use a third-party reporting tool, like Quadrotech’s Nova, to help you get better insights into the mailboxes being used – and who is using them – to help in your planning. 

Some users are facing issues in creating Team meetings from Outlook 2016 after migration, Once the meeting starts and they are the Organizer, it says ‘Someone from the meeting room will let you in shortly’. Any suggestions? 

This one is a real plain. The main issue in the move is that the meeting links change. For firms that have migrated between conferencing firms, you know this pain first-hand. In a tenant to tenant migration, these links will also need to be updated just as if you were changing solutions. 

Some firms have attempted to use the Meeting Migration Service with mixed results. It isn’t designed for tenant migrations, so I would recommend testing this first to see if it helps your situation. You can find this here.

If you have any additional questions on Office 365 tenant migrations and would like to speak to our expert team, please contact us today. We’re always happy to talk about everything tenant migration and management.