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We are migrating from a DC and Exchange 2003 on an old Win 2003 server to Win 2008 R2 and Exchange 2010 in a virtual env.

We are worried hardware failure in our old server when we install adprep and other migration prep stuff on it (it has trouble rebooting). All we have are tape backups of server data.

What are our options to implement temporary disaster recovery for the duration of the migration with minimal impact on our old server?

Some downtime is not a big deal. But we couldn't cope with 1 week downtime while we rebuild the DC and exchange from scratch. At the moment we are considering renting a server for several weeks to use as a hot spare.

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You don't have a current backup plan? Ouch. I don't think you would have a hardware failure with just running adprep unless you have something going really wrong with the health of your current AD. –  Nixphoe Jul 27 '11 at 14:09
    
You'll need to be more specific for temporary disaster recovery question. It sounds like you already have that with your tape backups. Are you looking for something more? –  Nixphoe Jul 27 '11 at 14:19
    
Yep Nixphoe. Backup to tape is our backup plan. The server struggles to reboot - the disk plate needs to be reset. If we could avoid a reboot I might close my eyes and try it but I think reboots of the original server are required for both AD and exchange upgrades. Otherwise I would close my eyes and just do it. –  RMNVM Jul 27 '11 at 14:19
    
We don't have another server to restore to. And how easy would it be to completely restore AD and exchange from backup to a fresh server? –  RMNVM Jul 27 '11 at 14:25

3 Answers 3

up vote 2 down vote accepted

Assuming you're doing a real migration (and not just starting a new AD forest and Exchange organization) you want to keep a good copy of Active Directory around.

If you can bring up a secondary domain controller on even a PC-class machine it'll help matters out. You don't want to lose all your copies of Active Directory or it'll make your life more complicated. This saves you from having to restore Active Directory in the event of a failure.

You can't restore System State backups to unlike hardware so, while I agree with @Vick Vega re: taking full backups (including System State) of your current servers, you can't restore them to other machines easily. Having a secondary domain controller makes this less of an issue (though you still need System State backups for off-site storage of AD backups).

Protecting Exchange from disaster during your recovery process is fairly straightforward. Perform online backups of Exchange and restore them if you need to. If the current server fails you can install a new machine, use the "/disasterrecovery" switch to install Exchange, and restore the online backup to it. There are no concerns about unlike hardware in restoring Exchange and, as long as the only thing on the box is Exchange, you really don't need to backup anything but the Exchange databases.

Edit:

The "PC-class machine" would have to be running Windows Server. I brought it up because you talked about impending potential hardware failure. I'd bring up a secondary DC quickly if I were concerned about failure of the original DC's hardware. You can go ahead and bring up your W2K8R2 DC as the secondary, too, but I got the feeling that it might take you some time to get there.

The /forestprep and /domainprep aren't "high-risk" updates in my experience. Obviously, have good backups before you start (though recovering from failed schema modifications are hard even if you do have good backups).

No matter what hardware you use, get a secondary DC up quickly if you're worried about hardware failure. Losing AD in this process isn't going to make it any easier. That will turn a straightforward migration into an ugly reconstruction.

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Interesting suggestion about pc-class machine. Wouldn't it have to be running win server 2003 though? And mightn't it be as easy to bring up a new domain controller on new 2008 R2 server as on another machine? From what I gather, running adprep /forestprep and /domainprep don't require reboots. Are these high risk updates to the DC? –  RMNVM Jul 27 '11 at 20:31
    
I'll drop on an edit. –  Evan Anderson Jul 28 '11 at 5:07
    
The fog is clearing. Thanks. Does this scenario make sense? We bring up a pc-class machine as a DC. But we restore a backup of Exchange 2003 onto a Win Server 2003 spare server (with space capacity) –  RMNVM Jul 28 '11 at 15:24

You should perform backup of the system state and then full backup of any files using NTBACKUP and follow the procedure as I described in the following post.

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In your post you say 'Create a machine with identical CPU type'. We do have a server with win 2003 64bit. But the processor type is x86. Should we install Win 2003 or could we continue with win 2003 64bit? –  RMNVM Jul 27 '11 at 20:56
    
Yes, that might be not entirely clear. Regardless of HARDWARE, the software, OS side of the installed system should be the same. So, if it was 32bit OS - install 32bit OS, if 64bit - than 64 bit OS. –  Vick Vega Jul 28 '11 at 15:44

I suggest looking into using VMWare Converter to convert your existing server to a virtual machine, thus elimiting your hardware problems.

AFAIK it is possible to pull a complete and exact image from a Windows machine while it is running and without rebooting.

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Ick... Converted machines are yucky. –  Evan Anderson Jul 27 '11 at 15:08

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