What you will learn in this tip: Microsoft System Center Data Protection Manager (DPM) is a solid backup application, but doesn't always meet the needs of every company. Here's how to decide whether or not it's a good fit for your organization.
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As a File System/Storage MVP, I have been involved with Microsoft's System Center Data Protection Manager since the beginning. Data Protection Manager is the backup application that I use to protect my own network. Even so, I will be the first to admit that Data Protection Manager isn't always the best fit for every organization's needs. Data Protection Manager does have some limitations you should be aware of.
Data Protection Manager and VSS writers
By far the biggest limitation for Data Protection Manager is the fact that it depends on underlying VSS writers. Unless an operating system contains a compatible VSS writer, Data Protection Manager simply cannot protect it. For example, Data Protection Manager is able to protect Windows Server 2003, Server 2008, Vista and Windows 7 because all of those operating systems have built-in VSS writers. However, Data Protection Manager cannot be used to protect Windows 2000 because it does not have a VSS writer.
In all fairness, Windows 2000 is about a decade old, and most organizations no longer use it. However, the requirement for a compatible VSS writer may still be an issue, particularly for organizations running non-Microsoft operating systems on some of their servers.
Even though all of the current Windows operating systems have the necessary VSS writer, that alone may not be enough. Having an operating system level VSS writer only guarantees that Data Protection Manager will be able to perform file system level backups of a protected computer. Sometimes, however, the applications that are running on a server may require their own VSS writers.
SQL Server presents a perfect example of this requirement. Because SQL servers contain active databases, you can't simply create a file-level backup of a SQL server, and expect the backup to work. That being the case, Microsoft provides a dedicated VSS writer for SQL Server that allows the databases to be backed up properly. The SQL Server VSS writer doesn't replace the operating system-level VSS writer, but rather augments it so that both the file system and the databases can be backed up.
The flipside to this requirement is that unless an application contains its own dedicated VSS writer, it may be impossible to back that application up using Data Protection Manager. Keep in mind that not all applications require a VSS writer. Some applications can be backed up at the file system level without any problems. As a general rule though, any application that uses a database typically requires a dedicated VSS writer.
Sometimes, there may be issues other than the lack of a compatible VSS writer that prevent Data Protection Manager from being a viable backup solution for an organization. You may sometimes find that Data Protection Manager simply won't back up a protected server, even if that server has all of the necessary VSS writers.
Replica is inconsistent errors
I have seen several real-world instances in which the initial synchronization of a protected resource fails, and Data Protection Manager simply indicates that the replica is inconsistent. Although Data Protection Manager does provide a means for performing a consistency check, sometimes all of the consistency checks in the world won't result in a usable replica. Other times you may find that the consistency check works, but an hour later the replicas may once again be in an inconsistent state.
For me this has been by far the most frustrating aspect of using Data Protection Manager. When I have spoken to some of the folks in Redmond about the issue, I've been told that the problem is not always directly related to the Data Protection Manager server itself. Instead, the issue can be related to conditions on the protected resource. For example, I've been told that if the protected server writes to virtual memory during a synchronization, it can cause the synchronization to fail. Synchronization can also fail if the protected server is low on memory or disk space, or if it is under a heavy load at the time of the backup.
If you have a server that does not have the required VSS writers, for instance, you might call your software vendor to see if a VSS writer is available. If you are dealing with replica inconsistencies, then you might consider opening a support incident with Microsoft and trying to resolve the issue before you have to invest in a new backup system. But in the end, you may discover that the only way that you can reliably protect the data on your network is by choosing a different backup application.
About the author: Brien M. Posey, MCSE, has previously received Microsoft's MVP award for Exchange Server, Windows Server and Internet Information Server (IIS). Brien has served as CIO for a nationwide chain of hospitals and was once responsible for the Department of Information Management at Fort Knox. You can visit Brien's personal website at www.brienposey.com.