Accessing shadow copies initiated by VSS

Snapshot Administration Guide for Hitachi NAS Platform

Part Number
The VSS Hardware Provider DLL provides support for taking shadow copies initiated by Microsoft's Volume Shadow Copy Service (VSS). The VSS Hardware Provider allows you to take shadow copies of iSCSI LUs located on storage devices managed by NAS servers. VSS shadow copies are exported as iSCSI LUs. After a shadow copy has been taken and exported (or "surfaced"), a pointer is provided to the application that requested the shadow copy. Using this pointer, the application can then access the shadow copy to back up database-type applications such as Microsoft Exchange and SQL Server.
Note: Creating a VSS shadow copy may result in a NAS server snapshot or a FileClone file clone being created on the NAS server.

The VSS Hardware Provider runs on a Windows server (see Installing the VSS Hardware Provider, on page 12). Once installed, the VSS Hardware Provider registers with the Microsoft VSS Service.

When a VSS shadow copy is created, one or more iSCSI LUs are added to the iSCSI target (one iSCSI LU is added for each source LU supplied to VSS). The shadow copy LUs are then visible to the VSS host (the system on which the VSS Hardware Provider is installed) and are used as the backup source.

Note: If a VSS snapshot request contains LUs on different file systems, then only one snapshot will be created for all the LUs in each file system. However, copies of each requested LU are always created and made visible to the VSS host by the NAS server.

Each NAS server or cluster must be configured to allow VSS access.