Because a snapshot set contains a split-mirror snapshot copy of each of the volumes in the Exchange component, the snapshot set requires the same amount of space as the original volumes. For Microsoft Exchange 2007, Exchange components are defined as storage groups. For Microsoft Exchange 2010, Exchange components are defined as databases.
Each snapshot set can be created as a different backup type: full copy including Eseutil consistency check and transaction log truncation, copy with Eseutil, or copy without Eseutil or transaction log truncation.
Snapshot set creation has the following stages, all of which you can schedule using the Quick Recovery Configuration Wizard:
Preparing the mirror for the snapshot set. This stage takes a while and should be scheduled for a time of low activity. The remaining stages take little time.
Creating the initial snapshot by splitting the mirror so that it is no longer synchronized with the original volume and becomes a point-in-time copy.
Refreshing (resynchronizing) the split-mirror snapshot with the original volume, and then splitting the mirror again. This stage occurs for each snapshot set at the times or frequency that you specify. For example, you can schedule one snapshot to occur every 30 minutes starting at 9 A.M. and ending at 6 P.M.