Some migration advice?

[PainOfDeath]

My company acquired another company that was running an Exchange server on a W2K3 DC (very bad, I know). This was the only server they had, serving about 30 users for mail, files, and printing. Let's call my company CompanyA and the acquired one CompanyB. At CompanyA we are using Imail version 6 serving about 30 users and we have no DCs or file servers (it's a retail business, most important functions are provided by a 3rd party ASP).

CompanyA wants to migrate to Exchange and I'd like to use CompanyB's server to do it, since it's a good Dell PowerEdge unit with redundant HDDs and PSUs. I decided to tear down CompanyB's domain because we need a different name, and because I don't want the Exchange server to be a DC.

What I've done so far:
- Set up a second DC for CompanyB and migrated file and print sharing to it (original DC still has all FSMO roles)
- Set up a new DC in a new forest for CompanyA
- Created accounts for all users in both organizations on this new DC

This was performed so I could physically relocate the Exchange server to CompanyA's office without disrupting services. I have a VPN set up and the two CompanyB DCs are working and replicating beautifully.

My next planned steps:
- Export all mailboxes on CompanyB's Exchange server to .PST files
- Backup the files on the second DC for CompanyB, demote it and remove it from the domain
- Uninstall Exchange from the DC and demote it, thus deleting this domain completely.
- Export mailboxes from the Imail server to .PST files
- Add this server (the PowerEdge) to the new CompanyA domain as a member server
- Install Exchange and import all mailboxes into the accounts I created.
- Promote the server I set up at CompanyB's site to a DC on the NEW domain and reinstate file/print sharing for those users.

I am reasonably experienced in W2K/2K3 administration but not so much with Exchange. Are there any important steps that I am missing here? Any hints/advice? I plan to use ExMerge to do the mail exporting/importing and all mailboxes are well under 2 GB. I am working on this alone and plan on doing the work on New Year's Eve/Day, and I obviously can't afford to have things go downhill come January 2. Most key users are using Outlook with local .PST files so I am not too worried about losing mailboxes, but more about not demoting the Exchange server correctly. I don't want to do a clean install on that machine because that will take more time that I don't really have because of the number of mailboxes I need to migrate and the timeframe involved.

Thanks for any help!

 

[markdmac]

I would advise using ADMT. ADMT will preserve SID history, user passwords and allow you to keep file ownerships the same.

Create a trust between the domains. Use ADMT to migrate the users & computers from DomainB to DomainA.

Add a second server to DomainB (not a DC). Move user data from DomainB to new server in DomainB.

Use ADMT to migrate the new server from DomainB to DomainA. This preserves user ownership of files etc.

Use ExMerge to export all mailboxes.

Remove Exchange from DomainB. Install Exchange in DomainA. Import PST files.

Use DCPROMO /ForcedRemoval to remove DomainB DC.

I hope you find this post helpful.

Regards,

Mark

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[PainOfDeath]

Thanks for your suggestions Mark - it turns out that there are actually now fewer than 10 users from CompanyB that will need to be migrated over, plus I have to change their user ID format from firstinitiallastname to firstname.lastname, and all their passwords have to change too. Also, since I am using the same hardware to run Exchange I have to migrate mailboxes out first, then remove it as a DC, then join it to the new domain and install Exchange, then import the mailboxes back in.