What is Volume Shadow Copy (VSS)?
by Clay Levering, on Jul 15, 2014 12:20:55 PM
As one of my jobs as the technical product manager for NovaBACKUP, I often take time to sit with our customer support team to understand the biggest issues facing their team and you, our customer. One of the most common issues they face (and the subject of this blog post) involves backing up open files and a Microsoft service called “Volume Shadow Copy.” Volume Shadow Copy Service (or VSS) is probably the single most important component of making sure you are getting backups of the files and systems that you need, and if it is having problems so will you.
What is Volume Shadow Copy?
According to its Wikipedia article, Volume Shadow Copy is:
“…a technology included in Microsoft Windows that allows taking manual or automatic backup copies or snapshots of computer files or volumes, even when they are in use.” – Wikipedia, Shadow Copy
A real world example I like to give when our users ask about VSS is to ask if they’ve ever tried to use an Excel document from a network share that someone else in their office has open on their machine. Excel will inevitably spit out an error (“This file is locked”) and you will not be able to do whatever it was you set out to do. The same situation can (and does!) happen when applications like NovaBACKUP are trying to back up your files.
Volume Shadow Copy is the service that allows applications like ours to get what is referred to as a, “transactionally consistent,” version of whatever file we are attempting to back up. This means we’re able to grab a version of that Excel document from a “safe” point in time, backing it up safely as though your coworker had closed it. By using specialized components of the Volume Shadow Copy service (VSS Writers), NovaBACKUP is capable of not only grabbing the best possible versions of your normal files, but also critical server applications like Microsoft Exchange, Microsoft SQL, Microsoft Hyper-V, Active Directory and the current Windows System State.
Problems with Volume Shadow Copy
As important as the Volume Shadow Copy service is for getting, “good,” versions of your files, it is no wonder that even the smallest problems can cause major issues with your backups. While our Support Portal offers quite a few different guides on helping you troubleshoot your potential VSS issues, I thought I’d outline a couple of the biggest bullet points.
Reboot the machine
Possibly the most often stated troubleshooting method in the history of computing: “Have you tried turning it off and on again?” It seems almost ridiculous that many of us have been using computers regularly for over two decades and it is just as likely that our IT desk asks us to reboot our computer today as it was 20+ years ago. That said, it is shocking to me how often this seems to resolve most issues with VSS (particularly SQL backups for some reason).
You can’t backup open files that are not on your computer
Many times, customers using shared network drives (like a shared “Home Drive” or similar) attempt to backup files that are not stored on their actual machine. Unfortunately, the Volume Shadow Copy service cannot create snapshots on drives that are not formatted in Microsoft’s NTFS file system or network file shares (special configurations of Server 2012 excluded). Thanks to how easy it is to use a mapped network drive in Windows, our support team regularly finds that customers have selected files they don’t actually have direct access to and VSS fails.
Make sure everything is up to date
Just like rebooting, making sure your workstation or server is fully up to date is critical to keeping Volume Shadow Copy reliably delivering copies of your opened files or applications to NovaBACKUP. While it seems the VSS service itself is not very prone to failure or bugs (anymore), version differences between your business applications like Exchange, SQL, Hyper-V or Active Directory and the operating system itself can definitely cause issues when it comes to backup. If you’ve recently run a system update, make sure there aren’t other updates that are now available for your other business applications.
Microsoft’s Volume Shadow Copy service is easily one of the most important – and one of the most delicate – pieces of a reliable backup plan. With a laundry list of vague error codes, constant “corner case” failures unique to specific environments and hundreds of thousands of Google results for every question, making sure that VSS is functioning correctly can be a daunting task even for an experienced system administrator.
With NovaBACKUP and our philosophy of, “Backup for the Rest of Us,” Volume Shadow Copy errors don’t mean the end of the world. With each purchase of NovaBACKUP Server or above, you get free setup assistance and a year of local telephone support to make sure everything is running, as it should. Our support team is here for you by making sure you can stop worrying about your backup plan and get back to what matters most: running your business.
Here are a few VSS troubleshooting tips from our support portal.