Volume Shadow Copy Service (VSS) snapshots

The Microsoft Volume Shadow Copy Service (VSS) enables application-consistent snapshots on volumes and specific applications used by Microsoft Windows. To enable VSS snapshots with the StorONE system, the StorONE VSS module must be installed on all Windows hosts or cluster members that use the volume.

In order for Microsoft VSS snapshots to be enabled:

• The StorONE volume must be block-based and directly mapped and formatted from the host (not through a hypervisor), or a virtual disk mounted as a drive letter on the host. Volumes used as virtual disks can be block or filesystem-based volumes (NFS). Network mapped shares cannot be used for Microsoft VSS snapshots with StorONE at this time.
• The Microsoft application must be VSS capable (Microsoft SQL, Exchange, Sharepoint, and so on).
• The StorONE VSS application must be installed on each Microsoft host where application consistent snapshots are required.  For Microsoft clusters, the VSS application must be installed on each individual cluster member.

Installing the StorONE VSS plugin on Microsoft Windows

Pre-requisites

You must install the latest Microsoft Visual C++ Redistributable Version package before installing the StorONE VSS plugin. It can be downloaded from Microsoft.

Download the relevant version for your Windows platform (x86 or x64).

If the StorONE VSS module was installed before installing the Microsoft Visual C++ Redistributable Version, remove the module, install the Microsoft Visual C++ Redistributable Version, and then reinstall the StorONE VSS module.

Downloading the StorONE VSS module

Download the latest VSS installer .MSI file from the StorONE landing page. In a browser, go to the DNS name or IP address of either of the StorONE controller nodes, and click the VSS Installer link.

Installing the StorONE VSS module

After the download completes, run the installer. Make sure to download and run it on all Windows machines (physical or virtual) that use the StorONE volume that you want to enable VSS snapshots on.

After the installation finishes, two services are added to the Windows host: S1VssHardwareProvider and S1VssService:

The hardware provider service should be set to manual start, as it only runs when Microsoft VSS snapshots are being taken.

When a Microsoft VSS snapshot is initiated by the StorONE system, the appliance contacts the VSS provider on the Windows machines on TCP port 18222. In order for application consistent snapshots to work properly, make sure that this port is open for requests from the management IP on both StorONE controller nodes.  VSS snapshots can be scheduled or manually initiated via the StorONE UI.

StorONE system configuration

In the StorONE admin web interface, there are two steps required to enable Microsoft VSS snapshots:

1. Enable VSS for the required volume
2. Configure a snapshot schedule

Step 1: Enable VSS

In the GUI, go to Applications 🡪 Snapshots, and then click the VSS button.

Specify the application and volume that you want to enable VSS snapshots for, and add the IP addresses of all Windows machines using the volume.

If the volume is a block volume (iSCSI or Fibre Channel) directly mapped to the Windows hosts, make sure to check the Direct Mapping checkbox.

If the volume is an NFS filesystem volume or a block volume used as a datastore hosting virtual disks for the Windows hosts, do not check the Direct Mapping checkbox.

Step 2: Configure snapshot schedule

On the Applications 🡪 Snapshots page, you can manually take a one-time snapshot by clicking the Take button, or by clicking Schedule to schedule recurring snapshots. In both cases, check the Enable Vss box.

When a VSS-enabled snapshot is initiated, the StorONE system will communicate with the VSS services on the Windows machines to coordinate an application-consistent snapshot.

Using the CLI

To manually take a Microsoft Application consistent snapshot using the CLI, use the --vss argument:

Troubleshooting

In some cases, the VSS backup fails with error 8194: Access Denied. This is caused when the Windows NETWORK SERVICE predefined local user does not have sufficient access permissions.

To fix this issue, add the relevant permissions:

1. Open the Windows Start Menu, then search for and run the dcomcnfg tool.
2. Expand the path Console Root 🡪 Component Services 🡪 Computers.
3. Right click on My Computer, then select Properties.
4. In the My Computer Properties dialog box, select the COM Security tab
5. In the Access Permission dialog box, click Add and enter NETWORK SERVICE.
   
6. To make sure the spelling is correct, click the Check Names button.
   
7. After adding NETWORK SERVICE make sure the Local Access permission is allowed.
   
   
8. Click OK to save the configuration.