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Restoring DAG from Bare Metal over two Subnets

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  • Restoring DAG from Bare Metal over two Subnets

    Hello all,

    This is my first post here and probably a question that cannot be answered easily.

    We have an Exchange 2010 setup here which I have inherited! (I hear the moans now!)

    The configuration is as follows:

    2 Mailbox servers
    2 CAS servers.

    One of each servers are in our main data centre and our DR data centre.

    We have a DAG.

    As these servers are in differnet data centers they obviously are in differnet subnets.

    I have been asked if i can prove our backup software by doing a Bare metal restore of the Exchange environment.

    I have sucessfuly restored the two head office servers using the software but cannot get the DAG to come online.

    I am guessing this si because I can only restore to a single subnet as this is done in a LAB environment where there is now switching ore subnets. This means I have to restore to differnet IP addresses.

    Is thre any way I can bring this back up using new IP addresses once restored?

    Or is this just a 'no go' senerio?

    Any thoughts welcome.



  • #2
    Re: Interesting request!

    I would NEVER do a bare metal restore of Exchange.
    Exchange isn't designed to be backed up or restored in that way.

    Backup the Exchange databases using an Exchange aware backup.
    Then build a replacement machine with the same name. Reset (not delete) the computer name, add to the domain, install Exchange with the recovery switches.
    Then restore the database in to that environment.

    That is the only way that Exchange should be recovered.

    If I have recovered an environment with a DAG from a backup, then I wouldn't expect the DAG to come back online. Trash the DAG and recreate, then reseed the database. You cannot restore both sides of the DAG from bare metal and expect it to work - it simply isn't going to work.
    Exchange is a living product, it is constantly changing. Any kind of image based backup is useless about 10 seconds after it has been taken - hence the recovery method I have outlined above.

    Of course, with two servers in two different subnets, a backup is almost completely unnecessary. If you were to lose both sites then you have bigger problems to worry about. Lose one site, the DAG retains the data, then you simply reseed the database to the new build server.

    Simon Butler
    Exchange MVP

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    • #3
      Re: Restoring DAG from Bare Metal over two Subnets


      Thank you very much for replying and posting such detail.

      You have confirmed for me what I have been trying to tell them here that this cannot be done sucessfully.

      As you also say if we loose both sites that we should have more to worry about than exchange not being online.

      I am now looking at putting in Exchange 2013 so am doing lots of reading about the best way to move forward with this.

      Thank you again for you reply.