The VSS snapshot utility creates snapshots (snapshot set) of all or specified volumes in the Exchange storage group or SQL database component. You can take the snapshots even when the application accesses these volumes.

Before you take a snapshot, the volumes in the required storage group on the Primary and the Secondary hosts must be prepared for the operation. The VSS snapshot operation uses the VSS service to quiesce the application and take a snapshot, after which it resumes the application. Before you resume the application, it sends an IBC message to the Secondary. The Secondary host is programmed to check for IBC messages at preset intervals, so that it can receive the IBC when it arrives.

IBC messages are typically used to ensure application-level consistency within an RVG. When the IBC arrives on the Secondary, it reads the message and freezes the replication so that the volumes do not change. The Secondary then completes the snapshot operation based on the information it has received through the IBC message.

The synchronous snapshots are initiated on the Primary and then on the Secondary at the same point of data consistency. An XML file containing the information about the volume metadata is maintained on the Primary and is used when while you reattach the snapshots.

You can either use vxsnap, the command line option, or the VSS Snapshot wizard to create the required synchronous snapshots.

For more information using the vxsnap command,

For information about using the VSS wizard,

Volume Replicator also provides a VSS Snapshot Scheduler wizard that enables you to set up a schedule for automating the snapback refresh process for synchronized snapshots. At the scheduled time for the snapshot, the snapshot volumes are automatically reattached, resynchronized, and then split again. The VxSchedService.exe scheduler service that maintains the schedule runs in the background.

For more information about using the VSS Snapshot Scheduler wizard,