How VSS and ShadowProtect Take Killer Backups

APRIL 10TH, 2014

As you may know, StorageCraft ShadowProtect uses VSS to create snapshots of a Microsoft computer volume. Snapshots are essentially a logical copy of the drive—a set of pointers to the actual information. Snapshots are often created to make an image-based backup.

The big questions here are: what exactly is VSS, why does ShadowProtect use it, and what makes it so awesome for creating solid backups? What is VSS? VSS is an acronym for Volume Snapshot Service (also known as Volume Shadow Copy Service). VSS is technology built inside Microsoft Windows that allows you to take either manual or automatic snapshot of your systems, even while applications are running, which is of course, the tricky part. VSS is a service that continually runs on your computer. The VSS service coordinates communication between three processes: a VSS requestor, a VSS writer, and a VSS provider. For example, Microsoft provides the VSS service which the ShadowProtect VSS requestor uses.  The VSS service then communicates with the various VSS writers registered by applications with the system before using the VSS provider to create the snapshot. This snapshot is then used by ShadowProtect to create an image-based backup. In this way, VSS allows you to take backups of a computer system, even while it’s in use (a hot backup) rather than requiring you to shut the system down (a cold backup). What does VSS have to do with ShadowProtect? According to our ShadowProtect User Guide, ShadowProtect uses the Windows VSS framework to provide consistent backups of SQLServer, Exchange, Active Directory, Oracle, or other database systems. VSS ensures that all cached data is written to disk (in other words, it makes sure all data is quiesced or frozen), prior to taking the snapshot. This is Microsoft’s recommended method for creating backups of Windows-based systems. ShadowProtect leverages VSS to create a point-in-time snapshot of an entire Windows system exactly as it is—whether it’s a server or a workstation. For these reasons, using VSS is the default for all ShadowProtect backup jobs. What role does ShadowProtect play in the VSS backup process? ShadowProtect acts as a VSS requestor. As we mentioned, ShadowProtect takes advantage of Microsoft’s VSS provider in order to implement backups. But what if for some reason Microsoft’s VSS processes fail? StorageCraft has also created a VSS provider included in every install of ShadowProtect software so it’s also possible to use ShadowProtect’s built-in VSS provider to create backups. What are the advantages of VSS over non-VSS backups? VSS was designed by Microsoft to help take backups of Microsoft systems. Because of that, it’s standard practice. Most applications that run on Windows are designed to work with VSS (though a handful of programs such as Intuit Quickbooks are non-VSS-aware), which means that nearly every scenario would be best served by a VSS backup. Again, this is why ShadowProtect backups have VSS enabled by default. Interested in trying StorageCraft ShadowProtect's solid backups? Download a free trial today. Photo Credit: Dnalor 01 via Wikimeda Commons 

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