Manage snapshottable directories and their snapshots.
 * 
 * This class includes operations that create, access, modify snapshots and/or
 * snapshot-related data. In general, the locking structure of snapshot
 * operations is: <br>
Manage snapshottable directories and their snapshots.
 * 
 * This class includes operations that create, access, modify snapshots and/or
 * snapshot-related data. In general, the locking structure of snapshot
 * operations is: <br> | SnapshotManager.java