You have a number of options for the location to recover data to—aside from the obvious choice of where the data is originally from. For SQL Server, you can restore a database over the database being protected or you can recover to an alternate SQL Server instance, to a network folder, or to tape. If you’re restoring an Exchange database, DPM can use the Recovery Storage Group (RSG) on an Exchange server, which lets you restore to the original Exchange server, overwriting the existing copy of the database; restore to another database on an Exchange server; restore to the RSG; restore to a network location; or copy to tape. For file resources, you can recover to the original location, an alternate location, or to tape.
You might not know where the data you want to restore is. As Figure 3 shows, DPM includes a search capability in the Recovery area that lets you search files and folders, Exchange mailboxes, and SharePoint sites or documents. The search returns a list of matches, which you can then select for recovery via the results window.
End-User Restores
So far I’ve talked primarily about administrator recovery options. You can enable end-user recovery for files on shares, a feature that utilizes the shadow copy client software available for DPM. This functionality will seem familiar for administrators who have enabled the Windows Shadow Copies of Shared Folders feature to let end users restore previous copies of their files from a share. DPM uses an updated version of the shadow copy client, so if you’ve deployed the previous client, you need to replace it with the new DPM-compatible version.
End users familiar with Shadow Copies of Shared Folders won’t notice a difference when using DPM. However, instead of snapshots of the share staying on the original file servers and using disk resources, DPM uses its own data store. To enable this redirection, you need to make a minor change to the Active Directory (AD) schema, which you can initiate via the DPM Administrator Console.
The shadow copy client is part of Windows Vista and downloads for Windows XP SP2 and Windows Server 2003 are available; you’ll find links for the specific downloads on the Microsoft web page “How to Install the Shadow Copy Client Software.”. When the client is deployed, you can select Restore previous versions on the context menu of an item to open the Previous Versions tab on the Properties sheet. As Figure 4 shows, the Previous Versions tab is populated via the information in DPM.
Bare-Metal Recovery
What do you do if the server itself dies and requires a bare-metal restore? DPM 2007 includes DPM System Recovery Tool (SRT), a bare-metal recovery solution that uses a separate agent on the protected clients. Although DPM SRT can be installed on DPM servers, it isn’t recommended due to the substantial differences in its I/O patterns. The great news is that you don’t need a separate license: Your DPM server license entitles you to install DPM on one server and DPM SRT on a separate server. The enterprise DPM license also lets you use both the DPM and DPM SRT agents; without an enterprise license, you’d need to license the agents separately.
DPM SRT protects servers not just from critical failures such as hard disk corruption but can also be used to restore a system that simply won’t boot and even to roll back changes such as updates. Essentially, DPM SRT has a complete copy of the entire content of a protected system. When you need to perform a restore, you use a customized Windows Preinstallation Environment (WinPE), which is provided as an ISO image as part of the DPM SRT solution. The WinPE allows media-based booting, or you can integrate the WinPE image into a Preboot Execution Environment (PXE) such as Windows Deployment Services for network-based recovery.
The other great feature of DPM SRT is that it uses Single Instance Storage (SIS). If you’re protecting 50 Windows 2003 servers, chances are that 99 percent of the files from each are duplicates. With SIS, these duplicate files are stored only once, meaning significant disk-space savings.
If you look at your DPM server by using the Microsoft Management Console (MMC) Disk Management snap-in, you’ll see two volumes for each protection group, as Figure 5 shows. The first volume is a copy of the latest data, and the second contains all the various recovery points. Although you shouldn’t manually mount or modify this data, understanding how it’s stored is useful in certain disaster-recovery scenarios—for instance, if DPM itself is unavailable but you have the protected data on a shared store such as a SAN, providing alternate access.
Just the Beginning
DPM has more advanced capabilities that I haven’t touched on. For example, you can run pre-backup scripts prior to synchronizations and post-backup scripts afterward, which lets you protect types of applications and data that DPM doesn’t natively understand. Going forward, we’re going to see DPM support more Microsoft solutions out of the box. Hopefully, Microsoft will partner with other companies so that third-party applications can take full advantage of the DPM store as well.
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