Mounting VSS Snapshots and Volumes

HPE VSS Services enables application-consistent snapshots for Microsoft Exchange and SQL Server. When a VSS snapshot is taken, several flags and attributes are set on the snapshot, and volumes cloned, promoted, or restored from that snapshot will inherit those flags and attributes. Before either a VSS snapshot or a volume cloned, promoted, or restored from a VSS snapshot can be properly mounted on a Windows host or cluster, the flags and attributes must be reset using the Set-NimVolume PowerShell cmdlet.

Using the Set-NimVolume PowerShell cmdlet is an additional step in the volume mounting workflow only when mounting a VSS snapshot, or a volume cloned, promoted, or restored from a VSS snapshot; mounting other types of volumes do not require the additional step.

NOTE: If you are mounting a clone created from a non-VSS (crash consistent) snapshot on the same host where the original volume is connected, and if the host is a Windows failover cluster, you must use diskpart to assign a new disk signature to the cloned volume before mounting it back to the original host. Disk resignaturing is not required when working with VSS snapshots, or when clones are connected to standalone hosts, regardless of whether the snapshot is VSS based or crash consistent.

To use the Set-NimVolume PowerShell cmdlet, you must know the snapshot or volume serial number or disk ID (Windows-assigned ID). Use one of the following methods to get this information:

  • Use the PowerShell Get-NimVolume cmdlet to obtain the serial number or disk ID.
  • Use piping with the Set-NimVolume and Get-NimVolume cmdlets.
NOTE: When mounting volumes restored from a VSS snapshot, or when promoting a volume on a DR site, the -NoDefaultDriveletter $false option must be specified so that the volume gets the same drive letter after restore as the original volume. The NoDefaultDriveLetter $false option should be ussed when you want the restored, promoted or cloned volume to have the same drive letter as that of the original volume.
NOTE: The ResetSnapshotInfo option must be specified when a cloned, promoted, or restored volume will be added to a Windows failover cluster.

The following three scenarios demonstrate where in the process you would use the Set-NimVolume PowerShell cmdlet when mounting a volume cloned or promoted from VSS snapshots.