Continuous Backup for Exchange Server 2013 with DPM 2012 (Part 3)
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Other Exchange 2013 Roles and Services
So far we’ve created protection for the Exchange mailbox databases, but what about the other Exchange roles and services?
In order to fully protect an Exchange Server 2013 infrastructure, other Exchange Server roles such as the Client Access Server should also have a recovery plan. Additionally, you should also consider protecting the transport service which resides on Mailbox servers.
Exchange Server data and configuration settings are spread amongst the file system, system state and Active Directory, and all these data sources can be protected with DPM 2012.
If DPM 2012 can also perform a complete bare-metal recovery of the protected servers. This recovery can be performed either to physical hardware or a virtualized infrastructure. It will also take significantly less time than reinstalling and configuring the host operating system on a replacement server in preparation for running the SETUP.EXE /m:RecoverServer Installation recovery routine.
After knowing what to backup in each server, configuring a dedicated Protection Group should be pretty straightforward. Figure 1, Figure 2 and Figure 3 depict an example, showing parts of the Protection Group wizard. The main difference in this case is in the Select Group Members page: instead of selecting mailbox databases, one must select the necessary volumes, System State and/or Bare Metal Recovery.
Figure 1: Select Group Members
Figure 2: Select Data Protection Method
Figure 3: All Protection Groups
Performance should be on top of mind of any Systems Administrators, especially when it concerns to protect data and computers. There are several factors that can impact performance, such as the hardware specs of the DPM server, network speed, hardware specs of the protected computer, size of the protected data and the rate at which the protected data changes.
Let’s take a deeper look on how all these factors influence the final performance and what measures can we take to mitigate potential risks.
DPM Server CPU and Memory
On the DPM server, three processes can impact performance:
- DPM protection agent (MsDpmProtectionAgent.exe): DPM jobs affect both memory and CPU usage by the DPM protection agent. It is normal for CPU usage by MsDpmProtectionAgent.exe to increase during consistency checks.
- DPM service (MsDpm.exe): the DPM service affects both memory and CPU usage.
- DPM Administrator Console (an instance of Mmc.exe): DPM Administrator Console can be a significant factor in high memory usage. You should close it when it is not in use
Under normal conditions, memory usage for the DPM instance of the SQL Server service (Microsoft$DPM$Acct.exe) is expected to be comparatively high. This does not indicate a problem, as the service normally uses a large amount of memory for caching, but it releases memory when available memory is low.
DPM Server Storage I/O
Since the storage subsystem can constitute a bottleneck, the following 2 measures can improve performance:
- Adding disks to the storage pool and reallocating the replicas across the storage pool can help reduce disk queue length.
- Using striped volumes can increase disk throughput to deal with disk bottlenecks.
DPM Data Transfer Operations
DPM data transfer operations have a huge impact on system and network resources. Let’s look at each of these operations individually and see what can be done to mitigate the risk of a bottleneck:
- Replica creation: Typically, the performance of the replica creation will be limited by the speed of the network connection between the DPM server and the protected computers. That is, the amount of time that it takes to transfer a 1-gigabyte (GB) volume from a protected computer to the DPM server will be determined by the amount of data per second that the network can transmit.The impact of replica creation on network performance can be reduced by using network bandwidth usage throttling.
- Synchronization: Synchronization is the process by which data changes are transferred from the protected computer to the DPM server and then applied to the replica of the protected data. For protected Microsoft Exchange data, synchronization transfers an incremental Volume Shadow Copy Service (VSS) snapshot.
Each synchronization job consumes network resources and can therefore affect network performance. The impact of synchronization on network performance can be reduced by using Network Bandwidth Usage Throttling and On-the-Wire Compression.
- Consistency check: A consistency check is the process by which DPM checks for and corrects inconsistencies between a protected data source and its replica. The performance of the protected computer, DPM server, and network will be affected while a consistency check is running, but the impact is significantly lower than initial replica creation, because only the changes and checksums are transferred. Consistency checks should be performed during off-peak hours.
- Express full backups: The impact of an express full backup operation on performance and time is expected to be less than the impact of a full backup because DPM transfers only the blocks changed since the last express full backup.
Network Bandwidth Usage Throttling
Network bandwidth usage throttling causes jobs to use less bandwidth, but they take longer to complete. To enable it, follow these guidelines:
- In DPM Administrator Console, click Management on the navigation bar. Click the Agents tab.
- In the Display pane, right click a server and select Throttle computer (Figure 4).
Figure 4: Throttle computer
- Click Enable network bandwidth usage. You can configure network bandwidth usage throttling separately for work hours and non-work hours, and you can define the work hours for the protected computer. Work hours and non-work hours use the time zone of the protected computer (Figure 5).
Figure 5: Throttle
On-the-wire compression decreases the size of data being transferred during replica creation and synchronization but increases CPU utilization on the DPM server and the protected computers. The amount of compression and improvement on network performance depends on workload.
Compression is enabled for a protected computer and applies to replica creation, synchronization, and consistency check operations. Recovery jobs also use compression.
To enable on-the-wire compression:
- In DPM Administrator Console, click Protection on the navigation bar. On the Actions menu, select Optimize performance.
- On the Network tab, select Enable on-the-wire compression. To apply your changes, click OK (Figure 6).
Figure 6: On-the-wire compression
DPM can be centrally monitored using System Center Operations Manager (SCOM). You use the Alert Publishing option only if you have chosen to centrally monitor your DPM servers in SCOM. This option synchronizes the DPM alerts that are displayed in the DPM Administrator Console with the Operations Manager console.
To publish existing DPM alerts, in DPM Administrator Console, in the Monitoring task area, click Options. In the Options dialog box, on the Alert Publishing tab (Figure 7), click Publish Active Alerts, and then click OK. On the pop-up message window (Figure 8), click OK.
Figure 7: Alert Publishing
Figure 8: Publish Active Alerts
After enabling the Alert Publishing option, all existing DPM alerts that might require a user action are published to the DPM Alerts event log (Figure 9). The Operations Manager agent that is installed on the DPM server then publishes these alerts to SCOM and continues to update the console as new alerts are generated.
Figure 9: DPM Alerts events
You can also configure DPM 2012 to send notifications by e-mail of critical, warning, or informational alerts, and the status of instantiated recoveries. If you plan to enable this feature, you must first configure the SMTP Server.
Follow these procedures to subscribe to notifications:
- In DPM Administrator Console, in the Monitoring task area, on the Action menu, click Options.
- Go to the SMTP Server tab (Figure 10), type the SMTP server name, the SMTP server port, and the e-mail address you want to display. In the Authenticated SMTP server area, type a user name and password in the appropriate boxes.
Figure 10: Configuring SMTP Server
- To test the SMTP server settings, click Send Test E-mail, type the e-mail address where you want DPM to send the test message, and then click OK.
- In the Options dialog box, on the Notifications tab, do the following:
- Select the types of alerts about which you want recipients to be notified.
- Under Recipients, type the e-mail address for each recipient to whom you want DPM to send copies of the notifications (Figure 11).
Figure 11: Configuring Notifications
- To test the SMTP server settings, click Send Test Notification. Click OK.
Backstage of Backups
Once the initial replication to the DPM server of the Exchange databases is made, synchronization will occur with the frequency that was configured for the short-term recovery points. The protection status of each storage group will be shown in the DPM Administrator Console (Figure 12).
Figure 12: Synchronizing Exchange Protection Group
The Exchange servers we’re using have 2 mailbox databases, CONTROL and KAOS, both being protected by the DAG (Figure 13).
Figure 13: Storage Groups and Mailbox Databases
Since this is not a production environment, all the Exchange data files (log files and databases) are located on the C: drive (Figure 14). Notice that there are 80 files in the folder.
When an Express Full Backup occurs, all the log files are pruned after a successful synchronization, since this is actually a full online backup (Figure 15).
Figure 14: Exchange data files
Figure 15: Exchange data files after Express Full Backup
If you remember part 1 of this series, it has been said that the synchronization process uses the Exchange VSS Writer. If we take a closer look to the Application Event Log of the protected Exchange server, we’ll notice a couple of events related with the VSS Backup (Figure 16, Figure 17, Figure 18 and Figure 19).
Figure 16: VSS Writer event 2021
Figure 17: VSS Writer event 2027
Figure 18: ESE Backup Event 961
Figure 19: VSS Writer Event 2046
If you open Server Manager, you can see the volumes created by the Protection Group (Figure 20), which are configured as mount points. If you right click one of them and select Change Drive Letter and Paths you can actually see the full path where those volumes are mounted to (Figure 21). This same information is also displayed in DPM Administrator Console, in the Protection task area, select a mailbox database and click the Replica Path hyperlink on the bottom pane (Figure 22).
Figure 20: DPM Disk Allocation
Figure 21: Volume Drive Letter and Paths
Figure 22: Details of Replica Path
Using Windows Explorer, you can browse to the location of those replicas (Figure 23), although I would not recommend that you mess with the files on those folders.
You will notice that the installation path of DPM contains three folders in the Volumes directory:
<Install Drive>\Program Files\Microsoft System Center 2012\DPM\DPM\Volumes\DiffArea - contains mounted shadow copy volumes that store the recovery points for a data source.
<Install Drive>\Program Files\Microsoft System Center 2012\DPM\DPM\Volumes\Replica - contains mounted replica volumes.
<Install Drive>\Program Files\Microsoft System Center 2012\DPM\DPM\Volumes\ShadowCopy - contains local backup copies of the DPM database.
Figure 23: Browsing the Volume Mounting Point
After spending 3 parts explaining the setup, configuration and operation of DPM 2012, the next part will cover one of the most exciting features introduced with SP1 for System Center 2012 DPM: the possibility to backup data to the Windows Azure cloud.
If you would like to read the other parts of this article series please go to: