Cross forest migration & O365 tenant migration

Question

Cross forest migration & O365 tenant migration

Marcus Wong Theen Nam 1,146

Currently I have a single forest and single domain setup in my environment. I need to separate some of the users out and move them to new AD forest with a new office 365 tenant since they belong to a different entity.
This will have two migration where I need to do a cross forest and office 365 tenant migration. I have below concerns for above migration:

How about the teams channel in source tenant that contains both users that is targeted to move to new forest and those that will be remain?
For file server and SharePoint server in my source forest, I just need to enable SID history and disable SID filtering in my SharePoint server?
For accounts after I migrated to new forest, the account will be left in my source forest as disabled account? Or it is gone from forest A?
Any other things that I need to care about?

Joyce Shen - MSFT 16,701 Reputation points

2022-09-23T02:41:53.557+00:00

Hi @Marcus Wong Theen Nam

For the third question you asked above, from Exchange side, yes they will be left in your source forest as disabled account.

Actually moving the mailboxes is a ‘two-step‘ procedure, first you pre-stage the move, this creates a Mail User in the new domain.*

Note: A Mail User is an a little bit like a Contact insofar as they both have external email addresses (i.e ‘*****@domaina.com’, while the mail user is in domainz.com, (until the mailbox is migrated). The difference between a Mail user and a contact is, a mail user has a logon name and a password. Once migrated the Mail User is converted into a User Mailbox in the new domain, and the User Mailbox back in old domain gets converted into a Mail User with an email address of *****@domainz.com for the mail user in domaina.com. This (while being cool) allows mail flow between the domains during migration.

For you other questions, I will help you add the related product tags, and if you want detailed answer for them, it is also suggested you ask the question separately with different tags. Thanks for your understanding!

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Joyce Shen - MSFT 16,701 Reputation points

2022-09-23T02:41:53.557+00:00

Hi @Marcus Wong Theen Nam

For the third question you asked above, from Exchange side, yes they will be left in your source forest as disabled account.

Actually moving the mailboxes is a ‘two-step‘ procedure, first you pre-stage the move, this creates a Mail User in the new domain.*

Note: A Mail User is an a little bit like a Contact insofar as they both have external email addresses (i.e ‘*****@domaina.com’, while the mail user is in domainz.com, (until the mailbox is migrated). The difference between a Mail user and a contact is, a mail user has a logon name and a password. Once migrated the Mail User is converted into a User Mailbox in the new domain, and the User Mailbox back in old domain gets converted into a Mail User with an email address of *****@domainz.com for the mail user in domaina.com. This (while being cool) allows mail flow between the domains during migration.

For you other questions, I will help you add the related product tags, and if you want detailed answer for them, it is also suggested you ask the question separately with different tags. Thanks for your understanding!

If an Answer is helpful, please click "Accept Answer" and upvote it.

Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.

Answer 1

Hi,

How about the teams channel in source tenant that contains both users that is targeted to move to new forest and those that will be remain?
If you are maintaining same UPN or whatever ImmutableID source anchor in the source domain it should match the AAD Account and do a softmatch to retain the acccess, read about this
For file server and SharePoint server in my source forest, I just need to enable SID history and disable SID filtering in my SharePoint server?
That is correct and all the groups that provide permissions should be migrated too for access and authorisation
For accounts after I migrated to new forest, the account will be left in my source forest as disabled account? Or it is gone from forest A?
Keep it disabled and it will stay as long as you dont hit the delete button
Any other things that I need to care about?
Carry out complete discovery and list down dependencies of the environment. Note down design the information of source and target domain, export all the users and groupd attributes incl AAD users.

Hope this helps.

==
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Marcus Wong Theen Nam 1,146 Reputation points

2022-09-24T10:09:40.777+00:00

Hi,
For No.1:
Since I'm not migrating all of my users to new forest and only migrating few of them. I will ended up with 2 forests and 2 different O365 tenant. So what I'm thinking of is the implement a B2B configuration in my O365 tenants to put back the users into source team channel as guest user. Or is there any other methods? Because the UPN will be different as well for those users that need to be migrated.

Answer 2

JimmySalian-2011 42,526

Yes guest invite will work with B2B if that is what you want and fulfulls the requirement why not. Think about long term planning and administration and If this answer helped you please mark it as "Verified" so other users can reference it.

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Cross forest migration & O365 tenant migration

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