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When it comes to Microsoft Visual SourceSafe (VSS), there’s more to backing up virtual machines (VMs) than meets the eye – even in VMware vSphere environments. Datacenters today place as much importance on application data as file data, especially data associated with high-priority applications like Microsoft SQL Server, Exchange, Active Directory and Oracle. This prioritization means your backup solution must protect your applications just as well as it protects your files, folders and VMs.
Protecting applications in the Windows world, however, isn’t always an easy task. Applications need special treatment if the data you’re capturing is in active use and must later be restorable. Virtualized applications require special treatment as well, and you also need to be aware of how your data protection solution integrates with Microsoft’s onboard Volume Shadow Copy Service (VSS).
Even VMware vSphere environments must respect Microsoft technology when it comes to application backups. Respecting how Microsoft VSS operates—and how your backup solution integrates with it—has become a mission-critical skill in modern data protection.
Microsoft VSS: What Every VMware Admin Needs to Know
Microsoft’s VSS, is Windows’ built-in infrastructure for application backups. A native Windows service, VSS facilitates the creation of a consistent view of application data during the course of a backup. It relies on coordination between VSS Requestors, Writers and Providers to quiesce—or “quiet”—a disk volume so backups can be obtained without data corruption.
That’s the technical definition. In simpler terms, VSS alerts the installed applications that a backup is about to take place. It coordinates backup activities between the OS and running applications. And it alerts the OS after backups are complete, instructing applications to perform important post-backup tasks, such as truncating logs and other application-specific cleanup activities.
Notwithstanding your hypervisor, VSS participation is generally necessary for backing up running applications on Windows servers. Those applications can be Exchange, SQL Server, Active Directory, Oracle or any application that requires constant access to files on disk.
Recall that the primary job of VSS is to “quiet” applications just prior to a backup. This action creates a point in time from which backups are then sourced. That point in time guarantees that the server, the applications and the backup solution maintain a consistent view of data.
Now, integrating your backup solution…
Although VSS has long been used for backing up running applications, it has become even more critical in virtual environments where entire VMs are backed up at once. This requires backing up a VM’s disk file as a point-in-time backup, a process that requires the same special treatment—and VSS quiescence—as applications.
In a sense, VMDK files are a lot like application databases in that a VM’s file system is always changing, and some mechanism to “quiet” the VM’s file system is needed for backups to maintain data consistency.
With VMware vSphere, that mechanism can be your chosen backup solution. This integration enables your backup solution to coordinate backup activities for the VM, while VSS coordinates the activities inside the virtualized application. One can further optimize backups with backup solution-specific VSS components. By leveraging the VSS framework inside each VM, additional intelligence can be added, such as log truncation of VSS-aware applications like SQL Server and Exchange.
Virtualization can greatly improve how entire servers get backed up and restored, but without the right tools, virtualization can also complicate data protection activities. Applications inside VMs require quiescence to be backed up successfully. So do VMs. The right approach integrates a modern data protection solution that’s built for virtualization and includes the onboard coordination provided by Microsoft’s Volume Shadow Copy Service.
But it doesn’t stop there. The solution your VMware vSphere environment demands is one that can restore any application and any VM with the same granularity and confidence you’d expect for any file and folder.