Exchange 2013 how to add database copy to DAG

The steps below will walk you through adding Databases to an Exchange DAG.  The action of adding Database copies to the DAG initiates replication between the servers storing copies of the database, increasing the availability of Exchange.  This article assumes that you have already created and configured the Exchange DAG.

Use the Exchange Admin Center (EAC) to add a mailbox database copy:

1) In the EAC, go to Servers > Databases.
2) Select the database that you want add to the DAG, and then click Add database copy.
3) On the “add mailbox database copy” page, click browse…, then select the Mailbox server that will host the new copy of the database, and then click OK.
Optionally, configure the Activation preference number for the database copy.
4) Click More options… to designate the database copy as a lagged database copy by configuring a replay lag time, or to postpone automatic seeding of the database copy.  Generally select the defaults here.  I generally only configure lagged copies when deploying a third or fourth DAG server.  I often select postpone seeding and then later go back in to resume the replication and seed the database.  I find this reducing seeding errors because the new database copy status can be replicated in AD before seeding is kicked off.
5) Click Save to save the configuration changes and add the new mailbox database copy.
6) Click OK to acknowledge any messages that appear.
Next, you’ll want to set the DAG’s DAC Mode.


13 thoughts on “Exchange 2013 how to add database copy to DAG

  1. jasdeep

    Thank you very very much…!!
    Actually i dont need to move the logs but my manager asked me to do so.
    Because he said that we will be in shortage of drive letters.(he said we will need 12+12 drive letters each server for DAG, but there are only 6+6 drives)
    We have 6 database drives and 6 log drives. A and C letters are already used.
    I dont understand why he told me that we will need total 24 drive letters.But in my knowledge we need only 12 (6 + 6 except C and A)
    You have any idea.

    Once again thank you

    1. Chris Harris Post author

      Hi Jasdeep,

      If you have 6 databases, that would be 6 transaction logs. I would use 12 drive letters on each DAG server. The drive letters used need to be identical between each member of the DAG.


  2. jasdeep

    Thank you very much…!!

    One more question about DAG.
    We have 2 Mailbox servers added disks for datastore coming from SAN.5 Databases each server.
    Now we want to add these to DAG.
    So I am worried that how should these work in a failover in case server 1 Fails. I mean the other databases are on server B and are not shared??

    1. Chris Harris Post author

      Your welcome. Re your question, if you have two existing Exchange 2013 servers each with existing databases and you want to add them to a DAG, in summary:
      – Make sure both on same CU
      Create the “DAG” (you’ve done this already it sounds like based on previous post). No data is moved or replicated at this point
      Add database copies to the DAG, you would add the databases from each server as a database copy on the other server. So the 5 DB’s on Server A would get added as Database copies on Server B and vice versa. Make sure you have enough disk space available as the entire dataset of each server will now exist on its partner.

      Again this is a summary, if you need specific steps for part of this let me know.

      A couple things, it’s recommended that you set the DAG DAC Mode.

      Often the initial database seeding fails. Wait 10-15 minutes and if it stays in a suspended state, try resuming if that doesn’t work you can use these steps to reseed suspended DAG database.

      1. jasdeep

        Hi Chris,
        Just like my past project of CU update, please help me in this as well.

        DAG Implementation
        Present scenario—
        BAC01MBX03 TARGET J: (351 GB) TOTAL MAILBOXES 77 space used 302 GB
        BAC01MBX04 TARGET L: (351 GB) TOTAL MAILBOXES 117 space used 299 GB
        BAC01MBX05 TARGET P: (351 GB) TOTAL MAILBOXES 83 space used 274 GB
        ARCMBX01 TARGET N: (699 GB)

        BAC02MBX01 TARGET F: (351 GB) TOTAL MAILBOXES 76 space used 272 GB
        BAC02MBX02 TARGET H: (351 GB) TOTAL MAILBOXES 86 space used 263 GB
        BAC02MBX05 TARGET P: (351 GB) TOTAL MAILBOXES 55 space used 148 GB
        Archive1Copy1 N: (699 GB)

        1. Implement DAG so that both of these Mailbox servers can hold the copies of each other’s Databases.
        2. Add 2 more drives (351 GB each) with Labels J & L to BACVSVRP012 so that these look similar in correspondence with other DAG server.
        3. Add 2 more log drives (69.9 GB each) with labels K & M to BACVSVRP012 for Logs for new J & L databases.
        4. Add the DAG servers for J & J, L & L, P & P, R & R, N & N .
        5. Move the mailboxes from F , H to new DAG datastores J & L respectively.

        Please pay attention let me know if i am wrong on anything.

        Thank you.

        1. Chris Harris Post author

          Re step 3, you will need matching log drives on each server so add K & M drives to BACVSVRP011. All database and log drives must be identical between servers for a given database/log set.

          Step 4 should be:
          Use ‘Add database copy’ function in GUI selecting BACVSVRP012 as for target server for database copies:
          TEMPDATABASE (see note below if you want to DAG replicate TEMPDATABSE)

          Use ‘Add database copy’ function in GUI selecting BACVSVRP011 as for target server for database copies:
          TEMPDATABASE (see note below if you want to DAG replicate TEMPDATABSE)

          NOTE: All database names must be unique, and I notice both servers have a database called “TEMPDATABASE”.

          1. jasdeep

            Hello Chris,
            One again you rock man.Thank you s ton.
            Yes, will sort the things and come back to you soon.

            Enjoy weekend.


            1. jasdeep

              One more thing,,,,What about the size remaining is all datastores??
              What should it be.Since there are disks of 351 GB and remaining size is between 70-50 GB.Will it work or i need to add space or move the mailboxes to another before DAG???

              1. Chris Harris Post author

                Hi Jasdeep,

                Essentially you’ll want to apply common sense on the disk space. Each volume needs enough space to hold all the databases and database copies that it will contain.
                It sounds like you have about 300GB of Databases on the volume in your example, so if that doubles due to replica’s from the other server then you would need 600 or more GB on the volume in order to hold the database that was already there plus the replica of the database from the other server.

                1. jasdeep

                  Hi Chris,
                  Please let me know the way to consolidate Database drive and Log file drive into one.
                  We are using different drives for Datastores and Log files.

                  Thank you

                  1. Chris Harris Post author

                    Hi Jasdeep,
                    It’s generally recommended to have separate database and log volumes, I would stick with that if you can. If you must combine them then this is basically a standard procedure of moving the Exchange database or moving the Transaction logs (examples of the exchange management shell commands are below). If you have DAG replicated the databases then you cannot move the database or transaction logs anymore, you lose that option. It can still be done but its very complicated and a big hassle. One way is taking the DB out of the DAG, moving it and then adding it back to the DAG.

                    Move the database example (for databases not in a DAG):
                    Move-DatabasePath “Mailbox Database 1” -EdbFilePath “M:\Mailbox Database 1\Mailbox Database 1.edb”

                    Move the transaction logs example:
                    Move-DatabasePath “Mailbox Database 1” -LogFolderPath “M:\Mailbox Database 1”

                    1. jasdeep

                      The databases are not in a DAG yet.

                      So after running the command–Move the transaction logs example:
                      Move-DatabasePath “Mailbox Database 1″ -LogFolderPath “M:\Mailbox Database 1″

                      will it move the existing logs as well or just it will be for the future logs.


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