How SnapDrive manages rolling Snapshot copies

When you initiate an Update Mirror operation, SnapDrive checks for any existing rolling Snapshot copies of the LUN containing the specified LUN drive

If SnapDrive does not find any rolling Snapshot copies containing the LUN image, it creates a rolling Snapshot copy on the SnapMirror source volume. SnapDrive then initiates a SnapMirror update operation, which replicates the rolling Snapshot copy on the destination volume.
If SnapDrive finds one rolling Snapshot copy, it creates a second rolling Snapshot copy and initiates a SnapMirror update.
If SnapDrive detects two rolling Snapshot copies for the LUN, it deletes the older rolling Snapshot copy and creates a new one to replace it. Then SnapDrive initiates a SnapMirror update.
Note: When you connect to a LUN in a Snapshot copy that is located on a traditional volume, SnapDrive creates a LUN backed by a Snapshot copy on the active file system. When a new Snapshot copy is created as part of a synchronous SnapMirror update, that new Snapshot copy will lock the Snapshot copy from which the LUN was connected. While the original Snapshot copy is locked, you will be unable to delete it until the next SnapMirror update when the first Snapshot copy is deleted automatically.