Using a snapshot of a replica for mailbox database recovery in Database Active Group (DAG)


Using a snapshot of a replica for mailbox database recovery in Database Active Group (DAG)
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A snapshot of a replica can be used to restore an Exchange mailbox database to the point of failure (POF) or to a point in time (PIT). Taking a snapshot of a replica can be done through the VEA GUI by using either the VSS snapshot wizard or with the vxsnap CLI command. Taking a snapshot of a replica automatically takes a snapshot of all the volumes that the replica uses.

When SFW fails to automatically dismount the database during a restore operation, the restore operation fails. The restore operation can be performed again after manually dismounting the databases and manually setting the databases for overwrite by restore.

Although SFW lets you restore the database from a snapshot, restoring just the database log files is not supported.

For an Exchange 2010 database that is configured under VCS cluster, offline the corresponding VCS database resource before the restore operation if automatic offlining of resource database fails. SFW automatically offlines the resource databases. Once the restore operation completes successfully, online the VCS resource database.

In other configurations, SFW dismounts the databases before the restore operation and then mounts the databases after the restore operation automatically.

Using the -a option automatically dismounts and mounts the databases. For a VCS cluster setup, it offlines and onlines the resource databases.

Refer to Microsoft Exchange 2010 Shell Help for details on Exchange cmdlets.

An example of a PIT recovery procedure from a snapshot of a replica copy of an Exchange mailbox database DB1 on an active mailbox database TestServer1and Replica copy on TestServer2 would be as follows:

Take Snapshot of the replica copy of mailbox database on TestServer2.
Use the Move-ActiveMailboxDatabase cmdlet to perform the active mailbox database DB1 switchover from Test Server 1 to Test Server 2.
```
Move-ActiveMailboxDatabase MB1 -ActivateOnServer TestServer2
```
Now TestServer2 has the Active mailbox database and TestServer1has Replica copy.
Use the Suspend-MailboxDatabaseCopy cmdlet to block replication and replay activities (log copying and replay)
```
Suspend-MailboxDatabaseCopy -Identity DB1\TestServer1 [ - Confirm:$False]
```
Use -Confirm to prevent user intervention
Use the Set-MailboxDatabaseCopy cmdlet to configure the properties of a database copy and set check box for "This database can be overwritten by Restore."
```
set-mailboxdatabase -identity MB1\TestServer2 -allowfilerestore:$true
```
Use the Dismount-Database cmdlet to dismount the database
```
dismount-Database -Identity MB1\TestServer2 [-Confirm:$False]
```
Use -Confirm to prevent user intervention

For a VCS cluster setup, offline the Exchange 2010 VCS resource database if automatic offlining fails.

Now perform the VSS restore operation using snapshot of replica.

vxsnap -x snapdata.xml restore RestoreType=
PIT writer="Microsoft Exchange Writer"

For this example, assume that the snapshot of the replica was performed with

vxsnap -x snapdata.xml create writer=
"Microsoft Exchange writer Replica" component=DB1 backupType=COPY -E -O

Use the Mount-Database cmdlet to mount database DB1
```
mount-Database -Identity DB1\TestServer2
```
For a VCS cluster setup, online the Exchange 2010 VCS resource database if automatic onlining of resource database fails.

Use the Update-MailboxDatabaseCopy

Update-MailboxDatabaseCopy 
-Identity MB3\TestServer2 -SourceServer TestServer1  - DeleteExistingFiles [-Confirm:$False]

Use -Confirm to prevent user intervention