Exchange 2013 to exchange 2016 migration

Prakash Modak 91

Hello,
i've 2 Forest and O365 Setup

Forest A ABC.ab with contoso.com suffix configured
ABC.ab domain controller
Exchange 2013 with two CAS & MBX servers and one DAG configured,
one Exchange 2013 server with CAS and witness role.
one reverse proxy for client access
one IMSVA for incoming /outgoing email filtering.

Forest B Contoso.com
contoso.com domain controller
ADconnect server
Planning exchange 2016 and migrate mailboxes and users from abc.ab forest.

O365 user syncing with contoso.com domain

I want to migrate mailboxes and users from forest A to forest B and then mailboxes to O365 (not all the mailboxes will be migrated).

Can you please suggest step by step migration from exchange 2013 to 2016 ?
Also suggest me the VM configuration required for 200 users .

Thanks in advance
Prakash

1 answer

Lydia Zhou - MSFT 2,371 Reputation points Microsoft Employee

2020-09-11T02:29:04.68+00:00

@Prakash Modak

What does "VM configuration required for 200 users" refer to? Please provide more explanation about what you want to configure for 200 users.

For the cross-forest migration from Exchange 2013 to 2016, you have to create mail users with required AD attributes in the target Forest B, then use the New-MoveRequest or the New-MigrationBatch cmdlets to move mailboxes, or move mailboxes in EAC. You can check this for more details about creating mail users with the necessary attributes: Prepare mailboxes for cross-forest move requests.
Here is a related blog about Exchange 2010 Cross-Forest Migration Step by Step Guide and ADMT can be used to migrate AD accounts.

Additionally, if you want to migrate mailboxes in Forest A to O365, why not configure the hybrid for Forest A directly? Hybrid deployments are supported for organizations with multiple on-premises Exchange forests and a single M365 or O365 organization. For your reference: Hybrid deployments with multiple forests.

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Lydia Zhou - MSFT 2,371 Reputation points Microsoft Employee

2020-09-15T06:47:51.953+00:00

@Prakash Modak

Just checking in to see if above information was helpful. Do you also consider to configure the hybrid for Forest A directly?
If you have any questions or need further help on this issue, please feel free to post back.

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Prakash Modak 91 Reputation points

2020-09-16T12:58:13.017+00:00

Thank you for your response,

as we would like to migrate eventually to forest B , hybrid for the forest A was ruled out.

for the 200 users, we have two mailboxes planned in new forest, executives and standard mailbox
the executive mailbox will have 10 GB mailbox limit & the standard mailbox will have 2GB mailbox limit.
No archive mailbox for any user ,

Thanks
Prakash

Lydia Zhou - MSFT 2,371 Reputation points Microsoft Employee

2020-09-17T08:45:06.867+00:00

Is domain name the reason to migrated to Forest B?
Will you keep some mailboxes on on-premise after migrating to Forest B?

If so, you can deploy the cross-forest migration as I mentioned above. If all mailboxes will be moved to O365 at last, you can just use the Exchange cutover method to move to O365. Then you still can deploy the hybrid for Forest B if needed. This is easier than cross-forest migration. For your reference: Migrate email using the Exchange cutover method.

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Lydia Zhou - MSFT 2,371 Reputation points Microsoft Employee

2020-09-17T08:46:28.257+00:00

@Prakash Modak

To deploy new Exchange environment for 200 users, you can use Exchange Server Role Requirements Calculator tool for more suggestions, and you can get it from: Ask the Perf Guy: Sizing Exchange 2016 Deployments.

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Prakash Modak 91 Reputation points

2020-09-17T14:06:57.357+00:00

Thank you ,

yes, the domain name is the reason to migrate to forest B, and forest B has ADconnect to O365 already configured.

Eventually, everything will be moved from forest A to Forest B, And between forest B and O365, it will be 80% mailbox migration to O365 and 20% On-premise.

Thanks
Prakash

Lydia Zhou - MSFT 2,371 Reputation points Microsoft Employee

2020-09-21T09:00:03.433+00:00

@Prakash Modak

Well, hope the articles provided above can help you. If you need other assistant for cross-forest migration, you're welcomed to post new questions.

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Prakash Modak 91 Reputation points

2020-10-22T14:43:16.003+00:00

i'm sorry for the late response, this project got canceled, hence i could not try anything
i'll surely try this whenever i get a change

Thank you so much for you efforts

Lydia Zhou - MSFT 2,371 Reputation points Microsoft Employee

2020-10-23T01:21:07.287+00:00

That's OK. If you have other issues about Exchange and need more assistant, please feel free to post with related tags.
Have a nice day.

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