Jeremy Phillips

Last Thursday night I had the distinct privilege of participating in a real life Exchange 2010 disaster recovery scenario. Roughly 41,000 mailboxes on 22 databases had the DAG ripped out from underneath them accidentally. When I say ‘ripped out from underneath them’ I mean literally that; everything was removed, including all the cluster resources and mailbox servers. As far as AD was concerned these servers didn’t even exist. All we had left was the .edb files, catalog indexes and log files. The solution? Database portability.

Even though this was essentially a test environment, there were a number of live mailboxes that simply had to be recovered and we wanted to recover them all. The steps we took were rather straightforward;

1 | Find some live mailbox servers that had the spare capacity to mount 22 databases. Split the list of databases to be mounted among them.

2 | For each mailbox server, copy over the database and log directories so we had the data to use.

3 | Perform a soft recovery with eseutil /r on each database/log set to commit any uncommitted log files and ensure we could actually mount the data later in the process.

4 | Create the new mailbox databases: new-mailboxdatabase -name <name> -server <server> -EdbFilePath <path to recovery folder, e.g. c:\RecoverDBs\RecoverDB1\<name of original edb>.edb> -LogFilePath <path to logs, e.g. c:\RecoverDBs\RecoverLogs1>

Pro Tip: Use a new name for the database. If the old database was named DAG1-DB001, you might use DAG1-RecoveryDB001.

5 | Set the newly created databases to allow file restore: set-mailboxdatabase <db name> -AllowFileRestore:$true

6 | Copy in the database, logs and catalog data to the correct folders (those specified in step 4)

7 | Mount the databases one at a time: mount-database <DatabaseName>

8 | Once the database is mounted we can now re-home all the users with mail data there: get-mailbox -database <OriginalDatabaseName> | ?{$_.ObjectClass -NotMatch ‘(SystemAttendantMailbox|ExOldDbSystemMailbox)’} | set-mailbox -database <RecoveryDatabaseName>

9 | If you’re running with multiple copies then keep in mind that you’ve only got one live copy of the new database. You can either add a copy of the new database or do what we did and move them to databases on your new DAG that (hopefully) has multiple copies already. If you choose to go the route of moving them to existing healthy databases the command is: get-mailbox -database <RecoveryDatabaseName> | new-moverequest -TargetDatabase <HealthyDatabaseName>

Comments and/or questions are welcome in the comments. I just wrote this from memory so if I missed anything along the way please let me know.